x86/net5501: remove broken flag

According to Christophe, the kernel boots on the Soekris net5501
board.

Reported-by: Christophe Prevotaux <cprevotaux@nltinc.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40468 3c298f89-4303-0410-b956-a3cf2f4a3e73