staging: rtl8723bs: make 'myid' function to follow kernel coding rules

Checkpatch.pl produced errors regarding inline keyword placement and
parenthesis around returned value in 'myid'.
Place inline after static keyword and remove mentioned parenthesis.

Signed-off-by: Maciek Fijalkowski <macfij7@wp.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>