Staging: rspiusb: Fix a bunch of warnings.

The patch fixes the following warnings.

drivers/staging/rspiusb/rspiusb.c: In function ‘pixel_data’:
drivers/staging/rspiusb/rspiusb.c:267: warning: passing argument 1 of ‘SetPageDirty’ makes
pointer from integer without a cast
drivers/staging/rspiusb/rspiusb.c: In function ‘UnMapUserBuffer’:
drivers/staging/rspiusb/rspiusb.c:500: warning: passing argument 1 of ‘put_page’ makes
pointer from integer without a cast
drivers/staging/rspiusb/rspiusb.c: In function ‘MapUserBuffer’:
drivers/staging/rspiusb/rspiusb.c:662: warning: assignment makes integer from pointer without a cast
drivers/staging/rspiusb/rspiusb.c:670: warning: assignment makes integer from pointer without a cast

Signed-off-by: Vibi Sreenivasan <vibi_sreenivasan@cms.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>