msm: smd_tty: Add locking hierarchy
msm: smd_tty: Add locking hierarchy

SMD TTY has several locks and it isn't clear what each lock manages.

Add a locking hierarchy and clarify locking scope.

Change-Id: I0026925a80548ef0025666d028b35e70d752a317
Signed-off-by: Eric Holmberg <5000aa55685d659e1f7f26ece526f9c7021ab484@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas