Fix some harmless type mismatches in the ARM atomic_cmpset implementations.

The return value of atomic_cmpset() and atomic_fcmpset() is an int (which
is really a bool) that has the values 0 or 1. Some of the inlines were
using the type being operated on (e.g. uint32_t) as either the return type
of the function, or the type of a local 'ret' variable used to hold the
return value. Fix all of these to just use plain 'int'. Due to C promotion
rules and the fact that the value can only be 0 or 1, these should all be
harmless.

Reviewed by: imp (only the v4 ones)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D15147