rpi_4_defconfig: add missing CONFIG_ARCH_FIXUP_FDT_MEMORY

As discussed at https://lore.kernel.org/linux-arm-kernel/b726290c-1038-3771-5187-6ac370bc92c9@arm.com/T/
the defconfig for rpi4 miss CONFIG_ARCH_FIXUP_FDT_MEMORY.
Without it, booting with an initrd fail.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
diff --git a/configs/rpi_4_32b_defconfig b/configs/rpi_4_32b_defconfig
index 52bdd0a..b22316c 100644
--- a/configs/rpi_4_32b_defconfig
+++ b/configs/rpi_4_32b_defconfig
@@ -7,7 +7,7 @@
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_OF_BOARD_SETUP=y
-# CONFIG_ARCH_FIXUP_FDT_MEMORY is not set
+CONFIG_ARCH_FIXUP_FDT_MEMORY=y
 CONFIG_MISC_INIT_R=y
 # CONFIG_DISPLAY_CPUINFO is not set
 # CONFIG_DISPLAY_BOARDINFO is not set