msm: 8960ab: Don't add gfx2d footswitches on 8960ab

8960ab doesn't have any gfx2d hardware, so we shouldn't add the
gfx2d footswitches on this device. By not adding them we avoid
probe errors in the kernel logs.

(cherry picked from commit 913c29d9696a86d93705afae14a1169f96d561b0)

Change-Id: I27ca48d4d7a58b5d752f1f0fcbc3eff5cfe20e1e
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Neha Pandey <nehap@codeaurora.org>