x86/boot/compressed: Move efi32_pe_entry into .text section

Move efi32_pe_entry() into the .text section, so that it can be moved
out of head_64.S and into a separate compilation unit in a subsequent
patch.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221122161017.2426828-5-ardb@kernel.org