clk: disable clk gate tests for s390

Currently clk-gate tests for s390 fail as the tests create a pretend
clk-gate and use a "fake_reg" to emulate the expected behavior of the
clk_gate->reg. I added some debug statements to the driver and noticed
that the reg changes after initialization to -1, which is coming from an
error coming from zpci_load(). This is likely because the test is using
fake iomem and the s390 architecture likely isn't designed to handle
that. Turn off the clk-gate tests for s390 for now as there is no clear
work around for this problem as discussed in upstream conversation [1].

[1] https://lore.kernel.org/all/301cd41e6283c12ac67fb8c0f8d5c929.sboyd@kernel.org/T/#tSigned-off-by: Audra Mitchell <audra@redhat.com>
Link: https://lore.kernel.org/r/20240702125539.524489-1-audra@redhat.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/Kconfig

@@ -514,6 +514,7 @@ config CLK_KUNIT_TEST
 config CLK_GATE_KUNIT_TEST
 	tristate "Basic gate type Kunit test" if !KUNIT_ALL_TESTS
 	depends on KUNIT
+	depends on !S390
 	default KUNIT_ALL_TESTS
 	help
 	  Kunit test for the basic clk gate type.