mkimage: Fix 'Unknown OMAP image type - 5'

mkimage: Fix 'Unknown OMAP image type - 5'

Using mkimage with e.g.

tools/mkimage -A arm -T firmware -O u-boot -d u-boot.bin foo.img

gives a warning

"Unknown OMAP image type - 5"

while it seems that the image itself is created successfully.

This does come from the patch "mkimage: Add OMAP boot image support".

The method check_image_type in image_type_params is supposed to just
return success or failure.  However, for omap it also calls fprintf:

static int omapimage_check_image_types(uint8_t type)
{
	if (type == IH_TYPE_OMAPIMAGE)
		return EXIT_SUCCESS;
	else {
		fprintf(stderr, "Unknown OMAP image type - %x", type);
		return EXIT_FAILURE;
	}
}

All the other image checkers and no others have this, so the fix is to
simply remove the fprintf.

Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>
CC: John Rigby <john.rigby@linaro.org>
CC: Aneesh V <aneesh@ti.com>
CC: Sandeep Paulraj <s-paulraj@ti.com>