objtool: Remove "ANNOTATE_NOENDBR on ENDBR" warning

This warning isn't very useful: why would you put ANNOTATE_NOENDBR on
ENDBR, and if you did, what's the harm?

And thus far it's only found one non-bug, where the
'__end_entry_SYSENTER_compat' label happens to land on the ENDBR from
entry_SYSCALL_compat:

  vmlinux.o: warning: objtool: entry_SYSCALL_compat+0x0: ANNOTATE_NOENDBR on ENDBR

.. which is fine.  Just remove the warning.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/142341a5dafdfc788e4c95b9e226a6eefc9b626e.1660839773.git.jpoimboe@kernel.org