memory: omap-gpmc: Clear GPMC_CS_CONFIG7 register on restore if unused

We want to clear any unused GPMC_CS_CONFIG7 register on restore to
ensure unused chip selects are not enabled.

Cc: Roger Quadros <rogerq@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20210727101034.32148-1-tony@atomide.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>