Minor optimisation to mcr20a-rf-driver code

This is a minor optimisation to the mcr20a-rf-driver code:
1. The function parameter is 'uint8_t *byteArray',  (byteArray == NULL) instead of using (byteArray == 0). The code is more readable.

Author: DavidLin1577

components/802.15.4_RF/mcr20a-rf-driver/source/MCR20Drv.c

@@ -165,7 +165,7 @@ void MCR20Drv_DirectAccessSPIMultiByteWrite
 {
     uint8_t txData;
 
-    if ((numOfBytes == 0) || (byteArray == 0)) {
+    if ((numOfBytes == 0) || (byteArray == NULL)) {
         return;
     }
 
@@ -230,7 +230,7 @@ void MCR20Drv_PB_SPIBurstWrite
 {
     uint8_t txData;
 
-    if ((numOfBytes == 0) || (byteArray == 0)) {
+    if ((numOfBytes == 0) || (byteArray == NULL)) {
         return;
     }
 
@@ -301,7 +301,7 @@ uint8_t MCR20Drv_DirectAccessSPIMultiByteRead
     uint8_t  txData;
     uint8_t  phyIRQSTS1;
 
-    if ((numOfBytes == 0) || (byteArray == 0)) {
+    if ((numOfBytes == 0) || (byteArray == NULL)) {
         return 0;
     }
 
@@ -338,7 +338,7 @@ uint8_t MCR20Drv_PB_SPIBurstRead
     uint8_t  txData;
     uint8_t  phyIRQSTS1;
 
-    if ((numOfBytes == 0) || (byteArray == 0)) {
+    if ((numOfBytes == 0) || (byteArray == NULL)) {
         return 0;
     }
 
@@ -406,7 +406,7 @@ void MCR20Drv_IndirectAccessSPIMultiByteWrite
 {
     uint16_t  txData;
 
-    if ((numOfBytes == 0) || (byteArray == 0)) {
+    if ((numOfBytes == 0) || (byteArray == NULL)) {
         return;
     }
 
@@ -473,7 +473,7 @@ void MCR20Drv_IndirectAccessSPIMultiByteRead
 {
     uint16_t  txData;
 
-    if ((numOfBytes == 0) || (byteArray == 0)) {
+    if ((numOfBytes == 0) || (byteArray == NULL)) {
         return;
     }