selftests/mm: skip uprobe vma merge test if uprobes are not enabled

selftests/mm: skip uprobe vma merge test if uprobes are not enabled

If uprobes are not enabled, the test currently fails with:

7151 12:46:54.627936  # # #  RUN           merge.handle_uprobe_upon_merged_vma ...
7152 12:46:54.639014  # # f /sys/bus/event_source/devices/uprobe/type
7153 12:46:54.639306  # # fopen: No such file or directory
7154 12:46:54.650451  # # # merge.c:473:handle_uprobe_upon_merged_vma:Expected
read_sysfs("/sys/bus/event_source/devices/uprobe/type", &type) (1) == 0 (0)
7155 12:46:54.650730  # # # handle_uprobe_upon_merged_vma: Test terminated by assertion
7156 12:46:54.661750  # # #          FAIL  merge.handle_uprobe_upon_merged_vma
7157 12:46:54.662030  # # not ok 8 merge.handle_uprobe_upon_merged_vma

Skipping is a more sane and friendly behavior here.

Link: https://lkml.kernel.org/r/20250610122209.3177587-1-pfalcato@suse.de
Fixes: efe99fabeb11 ("selftests/mm: add test about uprobe pte be orphan during vma merge")
Signed-off-by: Pedro Falcato <pfalcato@suse.de>
Reported-by: Aishwarya <aishwarya.tcv@arm.com>
Closes: https://lore.kernel.org/linux-mm/20250610103729.72440-1-aishwarya.tcv@arm.com/
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by : Donet Tom <donettom@linux.ibm.com>
Reviewed-by : Donet Tom <donettom@linux.ibm.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>