85xx: properly document MPC85xx_PORDEVSR2_SEC_CFG

Commit f7d190b1 corrected the value of MPC85xx_PORDEVSR2_SEC_CFG, but forgot
to add a comment that the correct value disagrees with the 8544 reference
manual.  The changelog for that commit is also wrong, as it says "bit 28"
when it should be "bit 24".

Signed-off-by: Timur Tabi <timur@freescale.com>

include/asm-ppc/immap_85xx.h

@@ -1579,6 +1579,7 @@ typedef struct ccsr_gur {
 #define MPC85xx_PORDEVSR_RIO_DEV_ID	0x00000007
 	uint	pordbgmsr;	/* 0xe0010 - POR debug mode status register */
 	uint	pordevsr2;	/* 0xe0014 - POR I/O device status regsiter 2 */
+/* The 8544 RM says this is bit 26, but it's really bit 24 */
 #define MPC85xx_PORDEVSR2_SEC_CFG	0x00000080
 	char	res1[8];
 	uint	gpporcr;	/* 0xe0020 - General-purpose POR configuration register */