spi: tegra20-slink: Declare runtime suspend and resume functions conditionally

spi: tegra20-slink: Declare runtime suspend and resume functions conditionally

The following build error is seen with CONFIG_PM=n.

drivers/spi/spi-tegra20-slink.c:1188:12: error:
	'tegra_slink_runtime_suspend' defined but not used
drivers/spi/spi-tegra20-slink.c:1200:12: error:
	'tegra_slink_runtime_resume' defined but not used

Declare the functions only if PM is enabled. While at it, remove the
unnecessary forward declarations.

Signed-off-by: Guenter Roeck <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Acked-by: Thierry Reding <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>