QcomModulePkg: Allocate gRXBuffer size to match requested size

Allocated fbd.gRxBuffer currently is 1MB which queued to
receive cmd from host is less than size of command requested
which is GetXfrSize() 16MB.

The command size buffer of more than 1MB can cause crash
on device, which is due to buffer overflow.

Change to allocate fbd.gRxBuffer equal to maximum requested
size.

Change-Id: I16c947412dc805c0ca7e364967c53120a824d3ad
diff --git a/QcomModulePkg/Library/FastbootLib/FastbootMain.c b/QcomModulePkg/Library/FastbootLib/FastbootMain.c
index ae01672..e06cf3b 100755
--- a/QcomModulePkg/Library/FastbootLib/FastbootMain.c
+++ b/QcomModulePkg/Library/FastbootLib/FastbootMain.c
@@ -60,7 +60,7 @@
 #include "FastbootMain.h"
 #include "UsbDescriptors.h"
 
-#define USB_BUFF_SIZE 1024 * 1024 * 1
+#define USB_BUFF_SIZE USB_BUFFER_SIZE
 
 /* Global fastboot data */
 static FastbootDeviceData Fbd;