staging: vchi: change type 'int32_t' to 's32'

As one can see in a typedef at linux/types.h:103, s32 and int32_t are
both a 32 bits signed integer. s32 is preferred because it is defined
by the kernel maintainers and it prevents portability issues. Changed
to meet checkpatch criteria.
Signed-off-by: André Almeida <andrealmeid@riseup.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchi/vchi_mh.h

@@ -36,7 +36,7 @@
 
 #include <linux/types.h>
 
-typedef int32_t VCHI_MEM_HANDLE_T;
+typedef s32 VCHI_MEM_HANDLE_T;
 #define VCHI_MEM_HANDLE_INVALID 0
 
 #endif