msm: thermal: Initialize sysfs attributes to quiet lockdep

Dynamically allocated sysfs attributes need to be initialized
with sysfs_attr_init() otherwise we get

 BUG: key ee1d8748 not in .data!

messages printed and lockdep becomes useless.

Change-Id: I74d9b6556f50d7e578569f67bb2c6b9b874cd64f
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>