vim: Disable parallel install, it has races

We end up with install errors when using high parallel factor like -j20

errors like

| mkdir: cannot create directory
`/``build/tmp-eglibc/work/ppce500v2-poky-linux-gnuspe/vim/7.4.27-r0/image/usr/share/vim/vim74':
File exists
| mkdir: cannot create directory
`/build/tmp-eglibc/work/ppce500v2-poky-linux-gnuspe/vim/7.4.27-r0/image/usr/share/vim/vim74':
File exists

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>