wimax/i2400m: use JUMP cmd for last FW chunk indication

Both secure and non-secure boot must set the JUMP command in the
bootmode header as the last FW chunk, so we change to use the JUMP
command to decide if the FW chunk download is completed.

Since we tend to use one single FW to support both secure and non-secure
boot for most of the time, I2400M_BRH_SIGNED_JUMP is actually found
even for non-secure boot. But in case the FW does come with
I2400M_BRH_JUMP, we check for both of them in i2400m_dnload_bcf().

Signed-off-by: Cindy H Kao <cindy.h.kao@intel.com>
Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>