net: phy: dp83848: Add comments for register definitions

#define TLK10X_PHY_ID			0x2000a210

/* Registers */

#define DP83848_MICR			0x11

#define DP83848_MISR			0x12

#define DP83848_MICR			0x11 /* MII Interrupt Control Register */

#define DP83848_MISR			0x12 /* MII Interrupt Status Register */

/* MICR Register Fields */

#define DP83848_MICR_INT_OE		BIT(0) /* Interrupt Output Enable */