arm: omap3: Directly use SMC #1 in lowlevel_init.S

arm: omap3: Directly use SMC #1 in lowlevel_init.S

Since commit de39dc71625d ("arm: armv7-a: Compile and tune for armv7-a
instead of armv5") is used -march=armv7-a option for Omap3 platforms.

With directive ".arch_extension sec" it is possible for -march=armv7-a to
directly use ARM SMC instruction.

So enable ".arch_extension sec" in Omap3 lowlevel_init.S and replace hand
assembled ".word 0xe1600071" by "SMC #1".

Since commit 51d063865064 ("arm: omap-common: add secure smc entry") same
pattern is already used in arch/arm/cpu/armv7/omap-common/lowlevel_init.S.

Signed-off-by: Pali Rohár <pali@kernel.org>