staging: mfd: hi6421-spmi-pmic: Simplify the compatible string

It is clear that this driver is for PMIC. So, get rid of
it at the compatible.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/12bdc9b4734e156098408d0d27256abdc91ac283.1597762400.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/hikey9xx/hi6421-spmi-pmic.c

@@ -323,7 +323,7 @@ static void hi6421_spmi_pmic_remove(struct spmi_device *pdev)
 }
 
 static const struct of_device_id pmic_spmi_id_table[] = {
-	{ .compatible = "hisilicon,hi6421-spmi-pmic" },
+	{ .compatible = "hisilicon,hi6421-spmi" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, pmic_spmi_id_table);