ARM: dts: omap4-droid4: Stop disabling SRAM and GPMC

I disabled SRAM and GPMC originally when seeing errors with
omap_barriers_init(). But that is no longer happening probably
because the memory range is now properly configured to 1021 MB
instead of 1024 MB. So let's enable SRAM and GPMC so we get
omap_barriers_init() working and can idle the GPMC.

Cc: Marcel Partap <mpartap@gmx.net>
Cc: Michael Scott <michael.scott@linaro.org>
Cc: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>