cxgb4: disarm endianness trouble waiting to happen in tw_fwcache()

'op' needs to be converted to __be32, not force-cast to it.  Fortunately,
right now it's only getting passed constant 0, but the same enum contains
a member equal to 1...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1 file changed