mpc5200: reduce delays in i2c

The previous code waited 1000us before checking i2c
status. Measurement shows i2c is usually ready in
under 50us. Change the polling interval to 15us,
loop 6,667 times to keep the polling timeout constant
at 100ms.

cpu/mpc5xxx/i2c.c

@@ -38,7 +38,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #error CONFIG_SYS_I2C_MODULE is not properly configured
 #endif
 
-#define I2C_TIMEOUT	100
+#define I2C_TIMEOUT	6667
 #define I2C_RETRIES	3
 
 struct mpc5xxx_i2c_tap {
@@ -94,7 +94,7 @@ static int wait_for_bb(void)
 		mpc_reg_out(&regs->mcr, 0, 0);
 		mpc_reg_out(&regs->mcr, I2C_EN, 0);
 #endif
-		udelay(1000);
+		udelay(15);
 		status = mpc_reg_in(&regs->msr);
 	}
 
@@ -109,7 +109,7 @@ static int wait_for_pin(int *status)
 	*status = mpc_reg_in(&regs->msr);
 
 	while (timeout-- && !(*status & I2C_IF)) {
-		udelay(1000);
+		udelay(15);
 		*status = mpc_reg_in(&regs->msr);
 	}