Staging: bcm: Replace dated variable __FUNCTION__ reported by checkpatch.pl

This patch replaces the obsolete variable, __FUNCTION__, that
holds the name of the current function with variable, __func__.

Signed-off-by: Kevin McKinney <klmckinney1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>