ARM: OMAP2: Fix the OMAP2 only build break seen with 2011+ ARM tool-chains

With the latest Sourcery G++ Lite 2011.03-41 and latest linaro
tool-chains OMAP2 only build breaks with below error.

arch/arm/mach-omap2/omap-smc.S: Assembler messages:
arch/arm/mach-omap2/omap-smc.S:30: Error: selected processor does not support ARM mode `smc #0'
arch/arm/mach-omap2/omap-smc.S:53: Error: selected processor does not support ARM mode `smc #0'
arch/arm/mach-omap2/omap-smc.S:61: Error: selected processor does not support ARM mode `smc #0'
arch/arm/mach-omap2/omap-smc.S:69: Error: selected processor does not support ARM mode `smc #0'
arch/arm/mach-omap2/omap-smc.S:77: Error: selected processor does not support ARM mode `smc #0'
make[1]: *** [arch/arm/mach-omap2/omap-smc.o] Error 1

OMAP2 devices doesn't have the security support but the security support
was getting built because of OMAP2PLUS. Don't build security code for
OMAP2 devices.

While at it, fix the secure-common line in the Makefile to use tabs
instead of spaces.

Reported-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>