mainboard/(i945,ich7): Remove commented RCBA32(0x341c) code

PCIe root port clock gate is already enabled at i945/early_init.c
Also fix comments when only PCIe root port is enabled.

Change-Id: Ica38529dbdd5cc51b19b426999a1d9f0b678b4f5
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37576
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/asus/p5gc-mx/early_init.c

@@ -94,7 +94,7 @@ static u8 msr_get_fsb(void)
 
 void mainboard_late_rcba_config(void)
 {
-	/* Enable PCIe Root Port Clock Gate */
+	/* Enable only PCIe Root Port Clock Gate */
 	RCBA32(CG) = 0x00000001;
 }