x86/paravirt: Remove unused paravirt bits

The macros ENABLE_INTERRUPTS_SYSEXIT, GET_CR0_INTO_EAX and
PARAVIRT_ADJUST_EXCEPTION_FRAME are used nowhere.

Remove their definitions.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: akataria@vmware.com
Cc: rusty@rustcorp.com.au
Cc: boris.ostrovsky@oracle.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20180828074026.820-10-jgross@suse.com