cfg80211: Validate cipher suite against supported ciphers

Instead of using a hardcoded list of cipher suites in nl80211.c, use a
shared function in util.c to verify that the driver advertises support
for the specified cipher. This provides more accurate validation of the
values and allows vendor-specific cipher suites to be added in drivers.

Change-Id: I649a1e896cadc1045701a8d5f93a83a7214fcda0
Acked-by: Jim Zmuda <jzmuda@qca.qualcomm.com>
Signed-off-by: Jack Cheung <jackc@codeaurora.org>