Give udhcpc more time and tries to request an IP address.
Give udhcpc more time and tries to request an IP address.

The udhcpc program is part of busybox and it looks like there is some
internal coordination when used with the busybox shell.
Now that the shell is replaced, that seems to be gone, so explicitly set
how it is supposed to function.

Signed-off-by: Diederik de Haas <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@cknow.org>

yodaaut/raspbian-ua-netinst