EmbeddedPkg/GdbSerialDebugPortLib: fix compile warning

The value of gTimeOut is from PcdGdbMaxPacketRetryCount, and this
PCD is UINT32. So change the declaratrion of gTimeOut to UINT32
to fix compile warning.

Signed-off-by: Wenyi Xie <xiewenyi2@huawei.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

Author: Wenyi Xie

EmbeddedPkg/Library/GdbSerialDebugPortLib/GdbSerialDebugPortLib.c

@@ -17,7 +17,7 @@
 #include <Protocol/DebugPort.h>
 
 EFI_DEBUGPORT_PROTOCOL  *gDebugPort = NULL;
-UINTN                   gTimeOut    = 0;
+UINT32                  gTimeOut    = 0;
 
 /**
   The constructor function initializes the UART.