spi: spi-mt65xx: Support sleep pin control

Supports configuring sleep pin control during system suspend to prevent
potential power leakage and additional power consumption.

Signed-off-by: Ruihai Zhou <zhouruihai@huaqin.corp-partner.google.com>
Link: https://msgid.link/r/20240108120802.7601-1-zhouruihai@huaqin.corp-partner.google.com


Signed-off-by: Mark Brown <broonie@kernel.org>