procd: drop nand_upgrade_stage1 from sysupgrade_pre_upgrade hooks

Now we have all targets using platform_pre_upgrade (and calling
nand_do_upgrade directly) we don't need nand_upgrade_stage1 to be in
sysupgrade_pre_upgrade hooks anymore.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

SVN-Revision: 47489