x86/alternative: Update text_poke_bp() kernel-doc comment

Update kernel-doc parameter name after

  c3d6324f ("x86/alternatives: Teach text_poke_bp() to emulate instructions")

changed the last parameter from @handler to @emulate.

 [ bp: Make commit message more precise. ]

Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20201203145020.2441-1-hqjagain@gmail.com