power: smb5: Prevent interrupt storm due to incorrect configuration

Commit 'f721be6a ("power: smb5: Advertise low battery in Type-C
Source mode")' changed the method of configuration of the
TYPE_C_INTERRUPT_EN_CFG_2 register from simple write to masked write.
This inadvertently led to the enabling of non-required interrupts and,
consequently, an interrupt storm.

Fix this by reverting to simple write.

Change-Id: I30e76c28b86e29eb40b1b73b29e1c77d8c73b29c
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>