net: Fix incorrect DHCP/BOOTP packets on 64-bit systems

net: Fix incorrect DHCP/BOOTP packets on 64-bit systems

This commit fixes incorrect DHCP/BOOTP packet layout caused by
'ulong' type size difference on 64 and 32-bit architectures.
It also renames NetReadLong()/NetCopyLong() to
net_read_u32/net_copy_u32() accordingly.

Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>