assemble_vintf: do not allow duplicated --kernel version.

For example, assemble_vintf ... --kernel=3.18... --kernel=3.18...
is not allowed.

Test: pass
Bug: 64124223
Change-Id: I339eec86f5ec6881ab0a2273d4e5e62b183e2333
Merged-In: I339eec86f5ec6881ab0a2273d4e5e62b183e2333
1 file changed