package/w_scan: needs kernel headers >= 3.3

w_scan needs SYS_DVBC_ANNEX_C, introduced in Linux 3.3.

Fixes:
    http://autobuild.buildroot.net/results/143/143960dc6de5377567dd2a383becc5a7bca90b41/



Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>