MIPS: bitops: Allow immediates in test_and_{set,clear,change}_bit

The logical operations or & xor used in the test_and_set_bit_lock(),
test_and_clear_bit() & test_and_change_bit() functions currently force
the value 1<<bit to be placed in a register. If the bit is compile-time
constant & fits within the immediate field of an or/xor instruction (ie.
16 bits) then we can make use of the ori/xori instruction variants &
avoid the use of an extra register. Add the extra "i" constraints in
order to allow use of these immediate encodings.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org