spi: ti-qspi: Fix mmap read when more than one CS in use

Commit 4dea6c9b ("spi: spi-ti-qspi: add mmap mode read support") has
has got order of parameter wrong when calling regmap_update_bits() to
select CS for mmap access. Mask and value arguments are interchanged.
Code will work on a system with single slave, but fails when more than
one CS is in use. Fix this by correcting the order of parameters when
calling regmap_update_bits().

Fixes: 4dea6c9b ("spi: spi-ti-qspi: add mmap mode read support")
Cc: stable@vger.kernel.org
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>