MIPS: ralink: mt7621: use bitwise NOT instead of logical

MIPS: ralink: mt7621: use bitwise NOT instead of logical

[ Upstream commit 5d8965704fe5662e2e4a7e4424a2cbe53e182670 ]

It was the intention to reverse the bits, not make them all zero by
using logical NOT operator.

Fixes: cc19db8b312a ("MIPS: ralink: mt7621: do memory detection on KSEG1")
Suggested-by: Chuanhong Guo <gch981213@gmail.com>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>