spl: fix linker size check off-by-one errors

This fixes SPL linker script size checks for 3 lds files where the size
checks were implemented as "x < YYY_MAX_SIZE".

Fix the size checks to be "x <= YYY_MAX_SIZE" instead.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>