cleanup op-tee core default log level

All targets already enable core debug log level: 3.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Tested-by: Jerome Forissier <jerome.forissier@linaro.org> (HiKey)
Tested-by: Joakim Bech <joakim.bech@linaro.org> (RPi3, MTK8173)
Tested-by: Etienne Carriere <etienne.carriere@linaro.org> (qemu_v7/v8)
diff --git a/qemu_v8.mk b/qemu_v8.mk
index 90abc18..7125bda 100644
--- a/qemu_v8.mk
+++ b/qemu_v8.mk
@@ -122,7 +122,7 @@
 # OP-TEE
 ################################################################################
 OPTEE_OS_COMMON_FLAGS += PLATFORM=vexpress-qemu_armv8a CFG_ARM64_core=y \
-			 DEBUG=0 CFG_PM_DEBUG=0 CFG_TEE_CORE_LOG_LEVEL=3
+			 DEBUG=0 CFG_PM_DEBUG=0
 optee-os: optee-os-common
 
 OPTEE_OS_CLEAN_COMMON_FLAGS += PLATFORM=vexpress-qemu_armv8a