stage2: preload ahci before udev/propagator

This change tries to force loading the storage driver
for cases when SecureBoot is "helping" the chainloader
to fail, see #29705 for details collected so far.

Of course ahci.ko only does AHCI but that's every storage
controller I've seen on UEFI/SecureBoot systems so far.

features.in/stage2/stage1/scripts.d/10-initrd-base

@@ -12,3 +12,6 @@ else
 fi
 
 echo 'FEATURES += propagator' >> /etc/initrd.mk
+
+# FIXME: #29705 workaround
+echo 'MODULES_PRELOAD += ahci' >> /etc/initrd.mk