power: qpnp-smb2: smb138x: change the vbus/vconn regulator_ops to static

Change the regulator_ops of vbus/vconn regulators in smb2 and
smb138x drivers to static. While at it, change the interrupt
handler smb138x_handle_slave_chg_state_change to static.

Change-Id: Iacd6b84adc6db1819b4a337aac9f6ccc52989dcd
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>