mfd: Add comments for the twl4030-power register and bit layout

Describe how the resource registers are laid out and the various bit-fields in
them.
Signed-off-by: Amit Kucheria <amit.kucheria@verdurent.com>
Cc: linux-omap@vger.kernel.org
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/twl4030-power.c

@@ -67,14 +67,22 @@ static u8 twl4030_start_script_address = 0x2b;
 #define R_KEY_1			0xC0
 #define R_KEY_2			0x0C
 
-/* resource configuration registers */
-
+/* resource configuration registers
+   <RESOURCE>_DEV_GRP   at address 'n+0'
+   <RESOURCE>_TYPE      at address 'n+1'
+   <RESOURCE>_REMAP     at address 'n+2'
+   <RESOURCE>_DEDICATED at address 'n+3'
+*/
 #define DEV_GRP_OFFSET		0
 #define TYPE_OFFSET		1
 
 /* Bit positions in the registers */
+
+/* <RESOURCE>_DEV_GRP */
 #define DEV_GRP_SHIFT		5
 #define DEV_GRP_MASK		(7 << DEV_GRP_SHIFT)
+
+/* <RESOURCE>_TYPE */
 #define TYPE_SHIFT		0
 #define TYPE_MASK		(7 << TYPE_SHIFT)
 #define TYPE2_SHIFT		3