ANDROID: kallsyms: strip the .cfi postfix from symbols with CONFIG_CFI_CLANG

With CFI enabled, LLVM appends .cfi to most function names, which
potentially breaks user space tools. While stripping the postfix is
not optimal either, this should at least create less confusion.

Bug: 67506682
Bug: 73328469
Change-Id: I253f34a562629032ddd792b8498e171109ea7cbc
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>