misc: Fix always compiling MISC even for SPL/TPL

We should only build support for misc if the appropriate SPL/TPL symbol
is defined. To ease the transition, make SPL/TPL_MISC default to MISC.
This is necessary because many drivers don't specify their dependencies
properly. These defaults can be removed once all drivers depend on the
appropriate config.

Fixes: aaba703f ("spl: misc: Allow misc drivers in SPL and TPL")
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
[trini: Add VPL_MISC symbol, handle like SPL/TPL_MISC]
Signed-off-by: Tom Rini <trini@konsulko.com>