powerpc/mpc85xx: Set default CONFIG_BUILD_TARGET

Final U-Boot binary for mpc85xx boards which use SPL and are not PBL-based
based is u-boot-with-spl.bin. PBL is not used only on boards with e500v1
and e500v2 cores. Apparently CONFIG_E500 is set not only for e500 cores,
but also for all other mpc85xx cores e500mc, e5500 and e5600. So do not use
CONFIG_E500 and instead filter new cores with PBL based bootrom.

Signed-off-by: Pali Rohár <pali@kernel.org>

Kconfig

@@ -461,6 +461,7 @@ config BUILD_TARGET
 	default "u-boot.itb" if !BINMAN && SPL_LOAD_FIT && (ARCH_ROCKCHIP || \
 				ARCH_SUNXI || RISCV || ARCH_ZYNQMP)
 	default "u-boot.kwb" if (ARCH_KIRKWOOD || ARMADA_32BIT) && !SPL
+	default "u-boot-with-spl.bin" if MPC85xx && !E500MC && !E5500 && !E6500 && SPL
 	default "u-boot-with-spl.bin" if ARCH_AT91 && SPL_NAND_SUPPORT
 	default "u-boot-with-spl.imx" if ARCH_MX6 && SPL
 	help