Makefile: Fix description for relocate-rela parameters

Numbers in comment are shifter which is visible from command which calls
them. Also relocate-rela usage is describing them.
"Usage: %s <bin file> <text base> <rela start> <rela end>"

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/bb0287b9071eb33eea0cf914a7128c2603684377.1655299267.git.michal.simek@amd.com