x86/entry: Rename idtentry_enter/exit_cond_rcu() to idtentry_enter/exit()

They were originally called _cond_rcu because they were special versions
with conditional RCU handling.  Now they're the standard entry and exit
path, so the _cond_rcu part is just confusing.  Drop it.

Also change the signature to make them more extensible and more foolproof.

No functional change -- it's pure refactoring.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/247fc67685263e0b673e1d7f808182d28ff80359.1593795633.git.luto@kernel.org