x86/fpu: Remove redundant XCOMP_BV initialization

fpu_copy_uabi_to_guest_fpstate() initializes the XCOMP_BV field in the
XSAVE header. That's a leftover from the old KVM FPU buffer handling code.

Since

  d69c1382 ("x86/kvm: Convert FPU handling to a single swap buffer")

KVM uses the FPU core allocation code, which initializes the XCOMP_BV
field already.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220324134623.408932232@linutronix.de