Staging: bcm2048 fix bare use of 'unsigned' in radio-bcm2048.c

This is a patch to the radio-bcm2048.c file that fixes up
a warning found by the checkpatch.pl tool.

Signed-off-by: Branislav Radocaj <branislav@radocaj.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>