of/fdt: Don't clear initial_boot_params if fdt_check_header() fails

of/fdt: Don't clear initial_boot_params if fdt_check_header() fails

If the device tree pointer is NULL, early_init_dt_verify() fails, leaving
initial_boot_params unchanged.  If the device tree pointer is non-NULL but
invalid, early_init_dt_verify() again fails but this time it also clears
initial_boot_params.

Leave initial_boot_params unchanged if the device tree pointer is invalid.
This doesn't fix a bug, but it makes the behavior more consistent and
easier to analyze.

Signed-off-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Zhen Lei <[email protected]>
Signed-off-by: Grant Likely <[email protected]>