defconfig: 8916: Disable unused configs

CONFIG_LEGACY_PTYS, CONFIG_INPUT_MOUSE are
not used.

Change-Id: I583a8524c396105c4f0cffa379b816d3b6ddb19f
Signed-off-by: Hanumant Singh <hanumant@codeaurora.org>
signed-off-by: Ravi Kumar siddojigari <rsiddoji@codeaurora.org>