sh: sh7724 mode pin comments

This patch adds comments for the sh7724 mode pins
and pin function controller.
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/include/cpu-sh4/cpu/sh7724.h

 #ifndef __ASM_SH7724_H__
 #define __ASM_SH7724_H__
 
+/* Boot Mode Pins:
+ *
+ * MD0: CPG - Clock Mode 0->7
+ * MD1: CPG - Clock Mode 0->7
+ * MD2: CPG - Clock Mode 0->7
+ * MD3: BSC - Area0 Bus Width (16/32-bit) [CS0BCR.9,10]
+ * MD5: BSC - Endian Mode (L: Big, H: Little) [CMNCR.3]
+ * MD8: Test Mode
+ */
+
+/* Pin Function Controller:
+ * GPIO_FN_xx - GPIO used to select pin function
+ * GPIO_Pxx - GPIO mapped to real I/O pin on CPU
+ */
 enum {
 	/* PTA */
 	GPIO_PTA7, GPIO_PTA6, GPIO_PTA5, GPIO_PTA4,