uboot-imx

boston: Drop unused return value

The boston lowlevel_init() function zeroes the return register v0,
despite the function not being expected to return a value & that value
never being used.

Remove the redundant assignment to v0.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>