crypto: mediatek - remove ARM dependencies

Building the mediatek driver on an older ARM architecture results in a
harmless warning:

warning: (ARCH_OMAP2PLUS_TYPICAL && CRYPTO_DEV_MEDIATEK) selects NEON which has unmet direct dependencies (VFPv3 && CPU_V7)

We could add an explicit dependency on CPU_V7, but it seems nicer to
open up the build to additional configurations. This replaces the ARM
optimized algorithm selection with the normal one that all other drivers
use, and that in turn lets us relax the dependency on ARM and drop
a number of the unrelated 'select' statements.

Obviously a real user would still select those other optimized drivers
as a fallback, but as there is no strict dependency, we can leave that
up to the user.

Fixes: 785e5c61 ("crypto: mediatek - Add crypto driver support for some MediaTek chips")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>