uboot-imx

console: Fix handling of NULL global_data

Both putc() and puts() can be called before global_data is set up. Some of
the code paths don't handle this correctly. Add an explicit test before
any member is accessed.

Reported-by: Coverity (CID: 169030)
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>