fix(versal-net): modify function to have single return

This corrects the MISRA violation C2012-15.5:
A function should have a single point of exit at the end.
Introduced a temporary variable to store the return value to
ensure single return for the function.

Change-Id: Ib8b3339f32031a3657f6c349763a20a99fd828e7
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
diff --git a/plat/xilinx/versal_net/include/plat_private.h b/plat/xilinx/versal_net/include/plat_private.h
index 0b82ca7..8b4020e 100644
--- a/plat/xilinx/versal_net/include/plat_private.h
+++ b/plat/xilinx/versal_net/include/plat_private.h
@@ -35,7 +35,7 @@
 
 extern uint32_t cpu_clock, platform_id, platform_version;
 void board_detection(void);
-char *board_name_decode(void);
+const char *board_name_decode(void);
 uint64_t smc_handler(uint32_t smc_fid, uint64_t x1, uint64_t x2, uint64_t x3,
 		       uint64_t x4, void *cookie, void *handle, uint64_t flags);
 int32_t sip_svc_setup_init(void);