mvebu: sysupgrade: sdcard: fix platform_do_upgrade_sdcard

mvebu: sysupgrade: sdcard: fix platform_do_upgrade_sdcard

Unconditionally execute the final case statement, even if the disk layout
changed. This is necessary, to keep the original Turris Omnia flash
instructions working: The disk layout WILL change, when switching from
TurrisOS to OpenWRT. Without updating the uboot environment at the same
time, the user would end up with an unbootable system.

Fixes commit 2e5a0b81ec ("mvebu: sysupgrade: sdcard: keep user added ...")

Signed-off-by: Klaus Kudielka <klaus.kudielka@gmail.com>