drivers: bcm: Mark functions as static in Qos.c

Mark functions MatchSrcIpAddress(), MatchDestIpAddress() and MatchTos()
as static in Qos.c because they are not used outside this file.

This eliminates the following warnings in Qos.c:
drivers/staging/bcm/Qos.c:27:6: warning: no previous prototype for ‘MatchSrcIpAddress’ [-Wmissing-prototypes]
drivers/staging/bcm/Qos.c:61:6: warning: no previous prototype for ‘MatchDestIpAddress’ [-Wmissing-prototypes]
drivers/staging/bcm/Qos.c:94:6: warning: no previous prototype for ‘MatchTos’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>