ARM: 7956/1: mmci: rename some extended flags

These four (so far unused) flags are only found in the ST Micro
versions of MMCI, so infix them properly with the _ST_ infix.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>