defconfig: 8909: Disable unused configs

CONFIG_LEGACY_PTYS, CONFIG_INPUT_MOUSE are
enabled by default.This causes the creation
of unused tty devices which impacts the userspace
ueventd processing at init time.Disable
these unused configs to improve boot time.

Change-Id: I4c7f59e0e1ab60eecb73f394c99fda3a05224219
Signed-off-by: Ravi Kumar S <rsiddoji@codeaurora.org>