Fix two remaining issues with the arm UFS mount issue:

Fix two remaining issues with the arm UFS mount issue:

- Add the GEOM_PART_GPT option and enable MSDOSFS in the GUMSTIX
  kernel. [1]

- Add GEOM_LABEL to the PANDABOARD kernel, that should have been
  included included in r285132.  I confused the kernel configuration
  used for the WANDBOARD and PANDABOARD, which the former uses the
  IMX6 kernel configuration, along with the CUBOX-HUMMINGBOARD.

This is a direct commit to stable/10, as was r285132.

[1] I do not actually have the GUMSTIX board, but I suspect it will
    fail to boot in the same way as the others have been.

Approved by:	re (kib)
Sponsored by:	The FreeBSD Foundation

git-svn-id: svn://svn.freebsd.org/base/stable/10@285365 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f