x86/tdx: Fix RETs in TDX asm

Because build-testing is over-rated, fix a few trivial objtool complaints:

  vmlinux.o: warning: objtool: __tdx_module_call+0x3e: missing int3 after ret
  vmlinux.o: warning: objtool: __tdx_hypercall+0x6e: missing int3 after ret

Fixes: eb94f1b6 ("x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220520083839.GR2578@worktop.programming.kicks-ass.net