kallsyms: get rid of code for absolute kallsyms

Commit cf8e8658

 ("arch: Remove Itanium (IA-64) architecture")
removed the last use of the absolute kallsyms.

Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/all/20240221202655.2423854-1-jannh@google.com/
[masahiroy@kernel.org: rebase the code and reword the commit description]
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>