habv4: tools: Avoid hardcoded CSF size for SPL targets

habv4: tools: Avoid hardcoded CSF size for SPL targets

Currently it's not possible to authenticate the U-Boot proper of
mx6ul_14x14_evk_defconfig target:

Authenticate image from DDR location 0x877fffc0...
bad magic magic=0x0 length=0x00 version=0x3
bad length magic=0x0 length=0x00 version=0x3
bad version magic=0x0 length=0x00 version=0x3
spl: ERROR:  image authentication fail

Commit 0633e134784a ("imx: hab: Increase CSF_SIZE for i.MX6 and
i.MX7 devices") has increased CSF_SIZE to avoid a possible issue
when booting encrypted boot images.

Commit d21bd69b6e95 ("tools: mkimage: add firmware-ivt image type
for HAB verification") is hardcoding the CSF and IVT sizes, the
new CSF size is not being considered and u-boot-ivt.img fails to
boot.

Avoid hardcoded CSF and IVT size to fix this issue.

Signed-off-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>