ARM: OMAP2+: Move omap_reserve() locally to mach-omap2

omap_reserve() callback is defned only for mach-omap2.
So, moving definition of omap_reserve() to mach-omap2.
This helps is moving plat/omap_secure.h local to
mach-omap2

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h
index b91b2a2..42b1b2e 100644
--- a/arch/arm/mach-omap2/common.h
+++ b/arch/arm/mach-omap2/common.h
@@ -343,6 +343,7 @@
 				      struct omap_sdrc_params *sdrc_cs1);
 struct omap2_hsmmc_info;
 extern int omap4_twl6030_hsmmc_init(struct omap2_hsmmc_info *controllers);
+extern void omap_reserve(void);
 
 #endif /* __ASSEMBLER__ */
 #endif /* __ARCH_ARM_MACH_OMAP2PLUS_COMMON_H */