ARM: dts: msm: change haptic mode for QRD8937 sku2

Haptic device node is defined by PMI8937. Haptics module
provides the vibration effects for the device. Change the
driver mode from lra to erm.

Change-Id: I2843ee7754ae19019fcf9311b75bb6b75803f363
Signed-off-by: Mao Li <maol@codeaurora.org>