Disable firmware user mode helpers

We don't need them and it causes issues for postmarket os where the user
mode helper takes a long time to complete.

Closes: #31
Signed-off-by: Guido Günther <guido.gunther@puri.sm>

arch/arm64/configs/librem5-evk_defconfig

@@ -136,8 +136,6 @@ CONFIG_FAILOVER=y
 CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
-CONFIG_FW_LOADER_USER_HELPER=y
-CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
 CONFIG_DEBUG_DEVRES=y
 CONFIG_CMA_SIZE_MBYTES=320
 CONFIG_VEXPRESS_CONFIG=y