OMAP: McBSP: Use appropriate value for startup delay

Increasing startup delay value as worst case:
 CLKSRG*2 = 8000khz: (1/8000) * 2 * 2 usec

Although, 100us may give enough time for two CLKSRG,
due to some unknown PM related, clock gating etc. reason,
this patch increases it to 500us.
Signed-off-by: Eduardo Valentin <eduardo.valentin@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

arch/arm/plat-omap/mcbsp.c

@@ -365,7 +365,13 @@ void omap_mcbsp_start(unsigned int id, int tx, int rx)
 	w = OMAP_MCBSP_READ(io_base, SPCR1);
 	OMAP_MCBSP_WRITE(io_base, SPCR1, w | (rx & 1));
 
-	udelay(100);
+	/*
+	 * Worst case: CLKSRG*2 = 8000khz: (1/8000) * 2 * 2 usec
+	 * REVISIT: 100us may give enough time for two CLKSRG, however
+	 * due to some unknown PM related, clock gating etc. reason it
+	 * is now at 500us.
+	 */
+	udelay(500);
 
 	if (idle) {
 		/* Start frame sync */