configs/qemu: update defconfigs to Linux 5.15

configs/qemu: update defconfigs to Linux 5.15

Remove upstream patch:

0001-sparc64-avoid-stringop-overread-warning-to-access-Ma.patch
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc7c028dcdbfe981bca75d2a7b95f363eb691ef3

0001-mips-Do-not-include-hi-and-lo-in-clobber-list-for-R6.patch
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1d7ba0165d8206ac073f7ac3b14fc0836b66eae7

0001-arch-s390-disable-SSP-when-needed.patch [3]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=42e8d652438f5ddf04e5dac299cb5e623d113dc0

Tested on gitlab:
https://gitlab.com/kubu93/buildroot/-/pipelines/402999845

Signed-off-by: Romain Naour <[email protected]>
Signed-off-by: Thomas Petazzoni <[email protected]>