ARM: OMAP3: Rename OMAP3_PUBLIC_SRAM_* to NON_SECURE_SRAM_*

ARM: OMAP3: Rename OMAP3_PUBLIC_SRAM_* to NON_SECURE_SRAM_*

Other TI processors like am33xx, omap4 and omap5 have called these variables
as NON_SECURE_SRAM_*, shouldn't be a big problem rename these variables to
be coherent.

One reason more to rename these variables is to have the possibility of any
OMAP3 board to use the ti_armv7_common.h include as the NON_SECURE_SRAM_END
is used to define the CONFIG_SYS_INIT_SP_ADDR variable.

Signed-off-by: Enric Balletbo i Serra <eballetbo@gmail.com>