phy: phy-core-mipi-dphy.c: Correct reference version

The rest of the code refers to version 1.2 of the MIPI D-PHY
specification. But this comment refers to 2.1, while a sub comment of
the function refers to 1.2 again. Replace 2.1 with 1.2.
Signed-off-by: Sebastian Fricke <sebastian.fricke@posteo.net>
Link: https://lore.kernel.org/r/20210421041740.8451-1-sebastian.fricke@posteo.netSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/phy-core-mipi-dphy.c

@@ -15,7 +15,7 @@
 /*
  * Minimum D-PHY timings based on MIPI D-PHY specification. Derived
  * from the valid ranges specified in Section 6.9, Table 14, Page 41
- * of the D-PHY specification (v2.1).
+ * of the D-PHY specification (v1.2).
  */
 int phy_mipi_dphy_get_default_config(unsigned long pixel_clock,
 				     unsigned int bpp,