ARM: OMAP: Fix 34xx to use correct shift values for gpio2-6 fclks

Wrong shift values were used for gpio2-6  fclks (gpt2-6 shift).

Signed-off-by: Jouni Högander <jouni.hogander@nokia.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>