spi: dw: fix wrong RX_SAMPLE_DLY setting after resume

spi: dw: fix wrong RX_SAMPLE_DLY setting after resume

On platforms which need a non-zero rx sample delay, the RX_SAMPLE_DLY
reg setting is lost after resume. The reason is that the reg may be
reset to 0 after resuming, but dws->cur_rx_sample_dly doesn't know
this fact. Fix this issue by clearing dws->cur_rx_sample_dly in
dw_spi_shutdown_chip().

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Suggested-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20260803135925.12622-1-jszhang@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>