ASoC: kirkwood-i2s: fix DCO lock detection

This is part of a patch found in Rabeeh Khoury's git tree for the
cubox, which is further attributed to Sebastian Hesselbrath.

Rather than masking the KIRKWOOD_DCO_SPCR_STATUS register contents
against the registers virtual address, let's actually use the bit
definition for the locked status, as required in the documentation.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/kirkwood/kirkwood-i2s.c

@@ -95,7 +95,7 @@ static inline void kirkwood_set_dco(void __iomem *io, unsigned long rate)
 	do {
 		cpu_relax();
 		value = readl(io + KIRKWOOD_DCO_SPCR_STATUS);
-		value &= KIRKWOOD_DCO_SPCR_STATUS;
+		value &= KIRKWOOD_DCO_SPCR_STATUS_DCO_LOCK;
 	} while (value == 0);
 }