Revert "serial: max310x: pass return value of spi_register_driver"

Revert "serial: max310x: pass return value of spi_register_driver"

This reverts commit d0656eb20853f52c1569635e8282773aa71a3339.

Because of recent interactions with developers from @umn.edu, all
commits from them have been recently re-reviewed to ensure if they were
correct or not.

Upon review, this commit was found to be incorrect for the reasons
below, so it must be reverted.  It will be fixed up "correctly" in a
later kernel change.

This change did not properly unwind from the error condition, so it was
not correct.

Cc: Kangjie Lu <kjlu@umn.edu>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20210503115736.2104747-11-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>