Commit e1b5bb6d ("consolidate cond_syscall
and SYSCALL_ALIAS declarations") broke the h8300 build because it removed
the duplicate SYMBOL_NAME() macro from arch/h8300/include/asm/linkage.h,
and all the h8300 asm files include <asm/linkage.h> instead of
<linux/linkage.h>:

    arch/h8300/kernel/entry.S: Assembler messages:
    arch/h8300/kernel/entry.S:158: Error: junk at end of line, first unrecognized character is `('
    ...
    arch/h8300/kernel/syscalls.S: Assembler messages:
    arch/h8300/kernel/syscalls.S:6: Error: junk at end of line, first unrecognized character is `('
    ...
    arch/h8300/lib/abs.S: Assembler messages:
    arch/h8300/lib/abs.S:12: Error: junk at end of line, first unrecognized character is `('
    ...
    arch/h8300/lib/memcpy.S: Assembler messages:
    arch/h8300/lib/memcpy.S:13: Error: junk at end of line, first unrecognized character is `('
    ...
    arch/h8300/lib/memset.S: Assembler messages:
    arch/h8300/lib/memset.S:13: Error: junk at end of line, first unrecognized character is `('
    ...

Commit 126de6b2 ("linkage.h: fix build
breakage due to symbol prefix handling") broke it even more, by removing
SYMBOL_NAME() and replacing it by __SYMBOL_NAME().

Commit f8ce1faf ("Merge tag
'modules-next-for-linus' of
git://git.kernel.org/pub/scm/linuxkernel/git/rusty/linux")
also removed __SYMBOL_NAME(), hidden in a merge conflict resolution.

Hence, replace the use of SYMBOL_NAME() and SYMBOL_NAME_LABEL() in h8300
assembler sources by hardcoding the underscore symbol prefix, like other
architectures (blackfin/metag) do.

This allows to kill SYMBOL_NAME_LABEL(). Now <asm/linkage.h> becomes empty,
and h8300 can be switched to asm-generic/linkage.h.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>