linux-user: removed unnecessary MAX_SOCK_ADDR checks for socket syscalls

- This check is not needed because kernel will check whether given
  buffer is too small and there is no upper limit for size of the buffer.

From: Mika Westerberg <mika.westerberg@iki.fi>

Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7117 c046a42c-6fe2-441c-8c8c-71466251a162
