fix(gicv3): return interrupt type to fix build

This patch fixes the following build fail observed in some
build environment:

1 error generated.
[2/24] CC secure_aem_v8a_fvp_clang/obj/src/arch/aarch64/plat/interrupts/gicv3.gicv3.o
FAILED: secure_aem_v8a_fvp_clang/obj/src/arch/aarch64/plat/interrupts/gicv3.gicv3.o
clang -MMD -MF secure_aem_v8a_fvp_clang/obj/src/arch/aarch64/plat/interrupts/gicv3.gicv3.o.d -DVM_TOOLCHAIN=0 -DGIC_VERSION=3 -DGICD_BASE=0x2f000000 -DGICR_BASE=0x2f100000 -DBRANCH_PROTECTION=1 -DHEAP_PAGES=60 -DMAX_CPUS=8 -DMAX_VMS=16 -DLOG_LEVEL=LOG_LEVEL_VERBOSE -DENABLE_ASSERTIONS=true -I../../inc -I../../inc/vmapi -I../../src/arch/aarch64/inc -Isecure_aem_v8a_fvp_clang/gen/offset_size_header -I../../src/arch/aarch64 -ffunction-sections -fdata-sections -flto -fno-builtin -ffreestanding -fpic -mcpu=cortex-a57+nofp -mstrict-align -mbranch-protection=standard -target aarch64-none-eabi -fcolor-diagnostics -nostdinc -isystem /home/mehhim01/Documents/FF-A/TFA_testing/hafnium/prebuilts/linux-x64/clang/lib64/clang/12.0.5/include -isystem /home/mehhim01/Documents/FF-A/tfa_testing_changes/hafnium/inc/system -g -Wall -O2 -Wpedantic -Werror -fstack-protector-all -std=c11 -c ../../src/arch/aarch64/plat/interrupts/gicv3.c -o secure_aem_v8a_fvp_clang/obj/src/arch/aarch64/plat/interrupts/gicv3.gicv3.o
../../src/arch/aarch64/plat/interrupts/gicv3.c:147:1: error: non-void function does not return a value in all control paths [-Werror,-Wreturn-type]

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: Ie6cdf9e854443d1848637bdd2885c5bf3d93c0b2
diff --git a/src/arch/aarch64/plat/interrupts/gicv3.c b/src/arch/aarch64/plat/interrupts/gicv3.c
index ef6d417..38883df 100644
--- a/src/arch/aarch64/plat/interrupts/gicv3.c
+++ b/src/arch/aarch64/plat/interrupts/gicv3.c
@@ -96,8 +96,9 @@
 /**
  * This function returns the type of the interrupt id depending on the group
  * this interrupt has been configured under by the interrupt controller i.e.
- * group1 Secure / group1 Non Secure. The return value can be one of the
+ * group0 or group1 Secure / Non Secure. The return value can be one of the
  * following :
+ *    INTR_GROUP0  : The interrupt type is a Secure Group 0 interrupt
  *    INTR_GROUP1S : The interrupt type is a Secure Group 1 secure interrupt.
  *    INTR_GROUP1NS: The interrupt type is a Secure Group 1 non secure
  *                   interrupt.
@@ -143,6 +144,9 @@
 	}
 
 	CHECK(false);
+
+	/* Else it is a Group 0 Secure interrupt */
+	return INTR_GROUP0;
 }
 
 /**