power: smb5: Disable/enable USBIN pulldown upon Type-C attach/detach

It is observed that commit 91480019 ("power: smb5: Fix OTG random
disconnection issue") causes an increase in bottom current when a Type-C
sink is connected. Fix this issue by disabling the pulldown on USBIN
whenever a Type-C sink or source is attached, and enabling it when it
has been detached.

CRs-Fixed: 2535589
Change-Id: If2a2ef612588464f1f0401a1b93ca3a0baacd4dc
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>