[POWERPC] QE: fix Kconfig 'select' warning with UCC_FAST

The UCC_GETH Kconfig option in drivers/net/Kconfig had a line to select the
UCC_FAST option is arch/powerpc/sysdev/qe_lib/Kconfig, which is only used
on PowerPC builds.  On other architectures, this would generated a warning.
The fix is to have UCC_FAST depend on UCC_GETH.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>