media: i2c: imx290: fix conditional function definitions

The runtime suspend/resume functions are only referenced from the
dev_pm_ops, but they use the old SET_RUNTIME_PM_OPS() helper
that requires a __maybe_unused annotation to avoid a warning:

drivers/media/i2c/imx290.c:1082:12: error: unused function 'imx290_runtime_resume' [-Werror,-Wunused-function]
static int imx290_runtime_resume(struct device *dev)
           ^
drivers/media/i2c/imx290.c:1090:12: error: unused function 'imx290_runtime_suspend' [-Werror,-Wunused-function]
static int imx290_runtime_suspend(struct device *dev)
           ^

Convert this to the new RUNTIME_PM_OPS() helper that so this
is not required. To improve this further, also use the pm_ptr()
helper that lets the dev_pm_ops get dropped entirely when
CONFIG_PM is disabled.

A related mistake happened in the of_match_ptr() macro here, which
like SET_RUNTIME_PM_OPS() requires the match table to be marked
as __maybe_unused, though I could not reproduce building this without
CONFIG_OF. Remove the of_match_ptr() here as there is no point in
dropping the match table in configurations without CONFIG_OF.

Fixes: 02852c01 ("media: i2c: imx290: Initialize runtime PM before subdev")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>