OMAP2&3: hwmod: Replace l3 -> l3_main

Replace all the struct that contain l3 with l3_main in order
to be consistent with the OMAP4 naming convention.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>