openssl: remove invalid quotes around x86_64

Thanks for Thomas for noticing.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/openssl/openssl.mk

@@ -18,7 +18,7 @@ endif
 ifeq ($(ARCH),powerpc)
 OPENSSL_TARGET_ARCH=ppc
 endif
-ifeq ($(ARCH),"x86_64")
+ifeq ($(ARCH),x86_64)
 OPENSSL_TARGET_ARCH=x86_64
 endif