nb/intel/sandybridge: Correct description of QCLK

QCLK means "quadrature clock", and is equivalent to one half of a full
clock cycle (tCK). Fix the comment. The `QCLK_PI` value is still valid.

Change-Id: I7089fc32381addc280a71761a377075f107b5c62
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49363
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/sandybridge/raminit_common.h b/src/northbridge/intel/sandybridge/raminit_common.h
index c43378d..b93902a 100644
--- a/src/northbridge/intel/sandybridge/raminit_common.h
+++ b/src/northbridge/intel/sandybridge/raminit_common.h
@@ -433,7 +433,8 @@
 #define MIN_CAS 4
 
 /*
- * 1 QCLK (quarter of a clock cycle) equals 64 PI (phase interpolator) ticks.
+ * 1 QCLK (quadrature clock) is one half of a full clock cycle (tCK).
+ * In addition, 64 PI (phase interpolator) ticks are equal to 1 QCLK.
  * Logic delay values in I/O register bitfields are expressed in QCLKs.
  */
 #define QCLK_PI	64