ARM: davinci: correct MDSTAT_STATE_MASK

MDSTAT.STATE occupies bits 0..5 according to all available documentation, so fix
the #define MDSTAT_STATE_MASK at last. Using the wrong value seems to have been
harmless though...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>