Blackfin: add support for the on-chip MAC status interrupts

This patch provides infrastructure for MAC Wake-On-Lan and PHYINT use in
phylib.  New Interrupts added:

IRQ_MAC_PHYINT   /* PHY_INT Interrupt */
IRQ_MAC_MMCINT   /* MMC Counter Interrupt */
IRQ_MAC_RXFSINT  /* RX Frame-Status Interrupt */
IRQ_MAC_TXFSINT  /* TX Frame-Status Interrupt */
IRQ_MAC_WAKEDET  /* Wake-Up Interrupt */
IRQ_MAC_RXDMAERR /* RX DMA Direction Error Interrupt */
IRQ_MAC_TXDMAERR /* TX DMA Direction Error Interrupt */
IRQ_MAC_STMDONE  /* Station Mgt. Transfer Done Interrupt */

On BF537/6 the implementation is not straight forward since there are now
two chained chained_handlers.  A cleaner approach would have been to add
latter IRQs to the demux of IRQ_GENERIC_ERROR.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>