msm: emac: Support for single core interrupt

The driver is designed to use four interrupts over four
cores. Probe will fail unless all four interrupts are
read from configuration and successfully registered.
Support is added for a single core platform.

Change-Id: I2e964b21615d7f2c381701faafe2480e558f98cd
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>