PCI/MSI: Rename __read_msi_msg() to __pci_read_msi_msg()

Rename __read_msi_msg() to __pci_read_msi_msg() and kill unused
read_msi_msg(). It's a preparation to separate generic MSI code from
PCI core.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index 8ab5add..90f756d 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -476,7 +476,7 @@
 		irq_set_msi_desc(virq, entry);
 
 		/* Read config space back so we can restore after reset */
-		__read_msi_msg(entry, &msg);
+		__pci_read_msi_msg(entry, &msg);
 		entry->msg = msg;
 	}