ARM: OMAP4: fix irq and clock name for dsp-iommu

Irq and clock names were wrong for dsp iommu configuration
for omap4.

- Renamed tesla_ick to dsp_fck:
   This is required because the new naming convention introduced
   by: commit 0e433271 "OMAP4 clock: Fix clock names and align
   with hwmod names"

- Renamed INT_44XX_DSP_MMU to OMAP44XX_IRQ_TESLA_MMU.
   Naming convention adopted since: commit e927f8d0 "omap4: Add
   auto-generated irq and dma headers"

- dsp-iommu is enabled by default.

Signed-off-by: Juan Gutierrez <jgutierrez@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>