spi: lpspi: add the error info of transfer speed setting

[ Upstream commit 77736a98b859e2c64aebbd0f90b2ce4b17682396 ]

Add a error info when set a speed which greater than half of per-clk of
spi module.

The minimum SCK period is 2 cycles(CCR[SCKDIV]). So the maximum transfer
speed is half of spi per-clk.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: 730bbfaf7d48 ("spi: spi-fsl-lpspi: Fix scldiv calculation")
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 3bb46e26783c3c86e67172f695908a066be69e12)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>