staging: fix csr printk format warning

Fix printk format warning on i386/X86_32 by using 't' for ptrdiff_t.
Also builds cleanly on x86_64.

drivers/staging/csr/csr_wifi_hip_udi.c: In function 'unifi_print_status':
drivers/staging/csr/csr_wifi_hip_udi.c:151:27: warning: format '%ld' expects type 'long int', but argument 5 has type 'int'

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>