x86/mmuext: unify okay/rc error handling in do_mmuext_op()

x86/mmuext: unify okay/rc error handling in do_mmuext_op()

c/s 506db90 "x86/HVM: merge HVM and PVH hypercall tables" introduced a path
whereby 'okay' was used uninitialised, with broke compilation on CentOS 7.

Splitting the error handling like this is fragile and unnecessary.  Drop the
okay variable entirely and just use rc directly, substituting rc = -EINVAL/0
for okay = 0/1.

In addition, two error messages are updated to print rc, and some stray
whitespace is dropped.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Make setting of rc happen consistently after MEM_LOG(), if that is being
used.

Signed-off-by: Jan Beulich <jbeulich@suse.com>