media: omap3isp: avoid warnings at IS_OUT_OF_BOUNDS()

Clang with W=1 produces the following warnings:

drivers/media/platform/omap3isp/isph3a_af.c:173:6: error: result of comparison of constant 256 with expression of type '__u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
        if (IS_OUT_OF_BOUNDS(paxel_cfg->height, OMAP3ISP_AF_PAXEL_HEIGHT_MIN,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/media/platform/omap3isp/isph3a_af.c:24:33: note: expanded from macro 'IS_OUT_OF_BOUNDS'
        (((value) < (min)) || ((value) > (max)))
                               ~~~~~~~ ^ ~~~~~
drivers/media/platform/omap3isp/isph3a_af.c:179:6: error: result of comparison of constant 256 with expression of type '__u8' (aka 'unsigned char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
        if (IS_OUT_OF_BOUNDS(paxel_cfg->width, OMAP3ISP_AF_PAXEL_WIDTH_MIN,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/media/platform/omap3isp/isph3a_af.c:24:33: note: expanded from macro 'IS_OUT_OF_BOUNDS'
        (((value) < (min)) || ((value) > (max)))
                               ~~~~~~~ ^ ~~~~~
2 errors generated.

Use a typecast to avoid such warnings.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>