BACKPORT: cfi: add C CFI type macro

Currently x86 and riscv open-code 4 instances of the same logic to
define a u32 variable with the KCFI typeid of a given function.

Replace the duplicate logic with a common macro.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Co-developed-by: Maxwell Bland <mbland@motorola.com>
Signed-off-by: Maxwell Bland <mbland@motorola.com>
Co-developed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Dao Huang <huangdao1@oppo.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250801001004.1859976-6-samitolvanen@google.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Bug: 452811419
Change-Id: I2c0a90b06f978c1fa8e70fb974b6cdaad123b3aa
(cherry picked from commit 5ccaeedb)
[liwei: fix minor conflict in arch/x86/kernel/alternative.c]
Signed-off-by: wei li <sirius.liwei@honor.corp-partner.google.com>