zephyr: emul: Set VBUS present in TCPCI
zephyr: emul: Set VBUS present in TCPCI

Set VBUS present on connecting source partner emulator to TCPCI only if
detection of VBUS is enabled (default). Clear present bit on partner
disconnection.

BUG=b:209907609
BRANCH=none
TEST=make configure --test zephyr/test/drivers

Signed-off-by: Tomasz Michalec <a547db31280d14f095c760a23a7523d0b1e55fe6@semihalf.com>
Change-Id: I8eced39e1fbaf6361327358c463d10904a871556
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3347660
Reviewed-by: Yuval Peress <50dc11c009bd4d7e9d9d15a383c1743ce5ee82ef@google.com>
Tested-by: Tomasz Michalec <c064a6042954d4ba0805003dc021b76413ff1548@google.com>
Commit-Queue: Tomasz Michalec <c064a6042954d4ba0805003dc021b76413ff1548@google.com>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec