KVM: s390: selftests: Streamline uc_skey test to issue iske after sske

KVM: s390: selftests: Streamline uc_skey test to issue iske after sske

In some rare situations a non default storage key is already set on the
memory used by the test. Within normal VMs the key is reset / zapped
when the memory is added to the VM. This is not the case for ucontrol
VMs. With the initial iske check removed this test case can work in all
situations. The function of the iske instruction is still validated by
the remaining code.

Fixes: 0185fbc6a2d3 ("KVM: s390: selftests: Add uc_skey VM test case")
Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Link: https://lore.kernel.org/r/20250128131803.1047388-1-schlameuss@linux.ibm.com
Message-ID: <20250128131803.1047388-1-schlameuss@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>