xhci-msm-hsic: Add support to handle channel ready gpio

Channel ready gpio is used to indicate channel readiness to
attached peripheral. This gpio was handled in platform specific
driver due to h/w limitations on older platforms. Add support to
handle this gpio from hsic driver and remove the support from
platform specific driver. Userspace peripheral handler will use
sysfs entry to assert channel readiness to peripheral
Sysfs entry and Usage:
echo 1 > /sys/devices/msm_hsic_host/host_ready

Change-Id: I8b41582360507e837f830f758838f62f7a55aa45
Signed-off-by: Vamsi Krishna <vskrishn@codeaurora.org>