x86/paravirt: Fix build due to __text_gen_insn() backport

The Link tag has all the details but basically due to missing upstream
commits, the header which contains __text_gen_insn() is not in the
includes in paravirt.c, leading to:

  arch/x86/kernel/paravirt.c: In function 'paravirt_patch_call':
  arch/x86/kernel/paravirt.c:65:9: error: implicit declaration of function '__text_gen_insn' \
  [-Werror=implicit-function-declaration]
   65 |         __text_gen_insn(insn_buff, CALL_INSN_OPCODE,
      |         ^~~~~~~~~~~~~~~

Add the missing include.

Reported-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/ZeYXvd1-rVkPGvvW@telecaster


Signed-off-by: Sasha Levin <sashal@kernel.org>