bugs/s390: Use 'cond_str' in __EMIT_BUG()

bugs/s390: Use 'cond_str' in __EMIT_BUG()

The simple thing would be to add the string as an assembly immediate
input operand. Some older gcc variants cannot handle strings as
immediate input operands for inline assemblies. Doing so may result in
compile errors.

Rewrite the s390 generic bug support very similar to arm64 and
loongarch, and get rid of all input operands to fix this.

  [ peterz: backmerge fix and massage changelog ]

  [ bp: clang integrated assembler concatenates only .ascii strings:
    https://lore.kernel.org/r/202507020528.N0LtekXt-lkp@intel.com ]

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org> # Fixed the tags section
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: linux-s390@vger.kernel.org
Link: https://lore.kernel.org/r/20250520133927.7932C19-hca@linux.ibm.com
Link: https://lore.kernel.org/r/20250617135042.1878068-3-hca@linux.ibm.com