uboot-imx

Fix Compilation Errors with 'tools/env/fw_printenv'

In the current top-of-tree, 1.3.3.-rc2, the optional tool
'tools/env/fw_printenv' fails to compile for two reasons:

1) The header watchdog.h cannot be found.
2) The header zlib.h is picked up from the tool chain rather than the
   project causing a prototype conflict for crc32.

This patch addresses both of these issues.

Platforms Tested On:
- AMCC "Kilauea"

Signed-off-by: Grant Erickson <gerickson@nuovations.com>