x86: drop dead asm-offsets definitions

x86: drop dead asm-offsets definitions

UREGS_user_sizeof had a use long, long ago on x86, and apparently was
blindly cloned into ARM code.

The uses of UREGS_saved_upcall_mask and UREGS_{ds,es,fs,gs} disappeared
in 71eb3a65e3 ("VMX: streamline entry.S code") and 110b2d6e8a ("SVM:
streamline entry.S code").

There are other ARM side UREGS_* which look to be unused, but I'd prefer
to leave deciding on their disposition to ARM folks.

irq_caps_offset and next_in_list_offset were introduced in 57b0566668
("Re-enable MSI support") without any user.

VCPU_failsafe_{addr,sel} and _VGCF_failsafe_disables_events uses went
away in d9b7ef209a ("x86: drop failsafe callback invocation from
assembly").

CPUINFO_processor_id looks to have been introduced without user by
917335d8b3 ("x86: Avoid assumptions about C struct layouts from asm
code").

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>