ARM: dts: am33xx: Reserve pm code and data regions in ocmcram sram node

Add a 'pm_sram_code' reserved region to the ocmcram node to be exposed
by the mmio-sram driver as a pool but also mark it protect-exec so that
it can run code copied to it using sram_exec_copy.

Add another 'pm_sram_data' reserved region to the ocmcram node to act as
the data space for any code running from the 'pm_sram_code' region that
is exposed as a regular pool.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>