Remove the assert on alignment check.

Also the alignment should only be done on general register types as
per the AAPCS so fixed that issue.

Copyright (c) 2020, Arm Limited.

src/librustc_codegen_llvm/va_arg.rs

@@ -128,8 +128,7 @@ fn emit_aapcs_va_arg(
     // it could be on the stack so we have to update the offset and then check
     // the offset again.
 
-    if layout.align.abi.bytes() > 8 {
-        assert!(layout.align.abi.bytes() <= 16);
+    if gr_type && layout.align.abi.bytes() > 8 {
         reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(15));
         reg_off_v = maybe_reg.and(reg_off_v, bx.const_i32(-16));
     }