nb/intel/x4x/raminit: Add missing space

TEST=Make the printk reachable, check with
     `strings build/cbfs/fallback/romstage.elf | grep lowest`
     that this patch changes "MHzas" to "MHz as".

Change-Id: I42033d2f184e424818edf844cf6cf84ea07d7ed5
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/29346
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/northbridge/intel/x4x/raminit.c

@@ -304,7 +304,7 @@ static void select_cas_dramfreq_ddr3(struct sysinfo *s,
 	min_tCLK = MAX(min_tCLK, saved_timings->min_tclk);
 	if (min_tCLK == 0) {
 		printk(BIOS_ERR, "DRAM frequency is under lowest supported "
-			"frequency (400 MHz). Increasing to 400 MHz"
+			"frequency (400 MHz). Increasing to 400 MHz "
 			"as last resort");
 		min_tCLK = TCK_400MHZ;
 	}