scripts/lld-version.sh: Rewrite based on upstream ld-version.sh

This patch is for linux-5.10.y only.

When scripts/lld-version.sh was initially written, it did not account
for the LLD_VENDOR cmake flag, which changes the output of ld.lld's
--version flag slightly.

Without LLD_VENDOR:

$ ld.lld --version
LLD 14.0.0 (compatible with GNU linkers)

With LLD_VENDOR:

$ ld.lld --version
Debian LLD 14.0.0 (compatible with GNU linkers)

As a result, CONFIG_LLD_VERSION is messed up and configuration values
that are dependent on it cannot be selected:

scripts/lld-version.sh: 20: printf: LLD: expected numeric value
scripts/lld-version.sh: 20: printf: LLD: expected numeric value
scripts/lld-version.sh: 20: printf: LLD: expected numeric value
init/Kconfig:52:warning: 'LLD_VERSION': number is invalid
.config:11:warning: symbol value '00000' invalid for LLD_VERSION
.config:8800:warning: override: CPU_BIG_ENDIAN changes choice state

This was fixed upstream by commit 1f09af06 ("kbuild: Fix
ld-version.sh script if LLD was built with LLD_VENDOR") in 5.12 but that
was done to ld-version.sh after it was massively rewritten in
commit 02aff859 ("kbuild: check the minimum linker version in
Kconfig").

To avoid bringing in that change plus its prerequisites and fixes, just
modify lld-version.sh to make it similar to the upstream ld-version.sh,
which handles ld.lld with or without LLD_VENDOR and ld.bfd without any
errors.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>