Remove the sole reference to __ARM_HAVE_BLX.

Every ARM processor we run on has blx.

Change-Id: I633984d208d8a1995b9595521352e0b16413837c
diff --git a/vm/arch/arm/CallEABI.S b/vm/arch/arm/CallEABI.S
index b90e8a8..d870306 100644
--- a/vm/arch/arm/CallEABI.S
+++ b/vm/arch/arm/CallEABI.S
@@ -254,12 +254,7 @@
     ldmia   r9, {r2-r3}                 @ r2/r3<- argv[0]/argv[1]
 
     ldr     ip, [fp, #8+FP_ADJ]         @ ip<- func
-#ifdef __ARM_HAVE_BLX
     blx     ip                          @ call func
-#else
-    mov     lr, pc                      @ call func the old-fashioned way
-    bx      ip
-#endif
 
     @ We're back, result is in r0 or (for long/double) r0-r1.
     @