bus: omap_l3_noc: use of_match_data to pick up SoC information

DRA7xx SoC has the same l3-noc interconnect ip (as OMAP4 and OMAP5), but
AM437x SoC has just 2 modules instead of 3 which other SoCs have.

So, stop using direct access of array indices and use of->match data and
simplify implementation to benefit future usage.

While at it, rename a few very generic variables to make them omap
specific. This helps us differentiate from DRA7 and AM43xx data in the
future.

NOTE: None of the platforms that use omap_l3_noc are non-device tree
anymore. So, it is safe to assume OF match here.

Signed-off-by: Sricharan R <r.sricharan@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
[nm@ti.com: split, refactor and optimize logic]
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Darren Etheridge <detheridge@ti.com>
Tested-by: Sekhar Nori <nsekhar@ti.com>