arm: omap5: fix build dependency for secure devices

Commit 17c2987 introduces an undesired dependency on CONFIG_SPL_LOAD_FIT
when building U-Boot for AM57xx and DRA7xx high-security (HS) devices that
causes the build to break when that option is not active. Fix this issue
by only building the u-boot_HS.img target when building U-Boot into an
actual FIT image.

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

arch/arm/cpu/armv7/omap5/config.mk

@@ -16,7 +16,7 @@ ALL-y	+= MLO
 endif
 else
 ifeq ($(CONFIG_TI_SECURE_DEVICE),y)
-ALL-y   += u-boot_HS.img
+ALL-$(CONFIG_SPL_LOAD_FIT) += u-boot_HS.img
 endif
 ALL-y	+= u-boot.img
 endif