x86/paravirt: Remove unused _paravirt_ident_32

There is no user of _paravirt_ident_32 left in the tree. Remove it
together with the related paravirt_patch_ident_32().

paravirt_patch_ident_64() can be moved inside CONFIG_PARAVIRT_XXL=y.

Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/20181030063301.15054-1-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>