KVM: Use .fixup instead of .text.fixup on __kvm_handle_fault_on_reboot

vmlinux.lds expects the fixup code to be on a section named .fixup. The
.text.fixup section is not mentioned on vmlinux.lds, and is included on
the resulting vmlinux (just after .text) only because of ld heuristics on
placing orphan sections.

However, placing .text.fixup outside .text breaks the definition of
_etext, making it exclude the .text.fixup contents. That makes .text.fixup
be ignored by the kernel initialization code that needs to know about
section locations, such as the code setting page protection bits.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>