omap4.inc: change to require tune-cortexa9.inc

As reported by Eric Bénard

Signed-off-by: Denys Dmytriyenko <denys@ti.com>

conf/machine/include/omap4.inc

@@ -1,7 +1,7 @@
 SOC_FAMILY = "omap4"
 require conf/machine/include/soc-family.inc
 
-require conf/machine/include/tune-cortexa8.inc
+require conf/machine/include/tune-cortexa9.inc
 
 PREFERRED_PROVIDER_virtual/kernel = "linux-omap4"
 PREFERRED_PROVIDER_virtual/bootloader = "u-boot"
@@ -23,4 +23,3 @@ UBOOT_ENTRYPOINT = "0x80008000"
 UBOOT_LOADADDRESS = "0x80008000"
 
 EXTRA_IMAGEDEPENDS += "u-boot"
-