arm: omap: Fix 'get_device_type()' for OMAP34XX

Fixes: 00bbe96e ("arm: omap: Unify get_device_type() function")

The control status register value is embedded in a structure somewhere
in SRAM, with the last refactoring effort. This patch allows OMAP3 EVM
(TMDSEVM3530) to boot again using the known control register base and
offset for 'readl', for the OMAP34XX case.

Signed-off-by: Derald D. Woods <woods.technical@gmail.com>
[trini: Change to if/else, add comment about it.]
Signed-off-by: Tom Rini <trini@konsulko.com>