spl: ymodem: Fix loading of fit image

spl ymodem driver always assumes that 1 BUF_SIZE is read in one stream.
This might not be true when image is not padded to BUF_SIZE and the last
sector that gets loaded will be < BUF_SIZE. Drop this assumption and use
the actual size that is loaded.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
1 file changed