vega_sdk_riscv: Ignore GCC warning about potential uninitialized variable

When -ffreestanding is not enabled, and GCC is able to use it's
knowledge of memset semantics, it sometimes gets it wrong, as in this
case. I'm not quite sure what is confusing it here, but the code sure
looks correct.

Signed-off-by: Keith Packard <keithp@keithp.com>

Author: keith-packard

vega_sdk_riscv/devices/RV32M1/drivers/fsl_cau3_ble.c

@@ -4077,6 +4077,11 @@ status_t CAU3_CHACHA20_POLY1305_SetKey(CAU3_Type *base, cau3_handle_t *handle, c
 
 static status_t cau3_load_nonce(CAU3_Type *base, const uint8_t *nonce, cau3_key_slot_t keySlot)
 {
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#endif
+
     union {
         uint8_t b[16];
         uint32_t w[4];
@@ -4092,6 +4097,9 @@ static status_t cau3_load_nonce(CAU3_Type *base, const uint8_t *nonce, cau3_key_
     tempIv.w[2] = __REV(tempIv.w[2]);
 
     return CAU3_LoadKeyInitVector(base, tempIv.b, keySlot, kCAU3_TaskDonePoll);
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#endif
 }
 
 status_t CAU3_CHACHA20_POLY1305_Encrypt(CAU3_Type *base,