ram: renesas: dbsc5: Fix off by 1 errors

ram: renesas: dbsc5: Fix off by 1 errors

In dbsc5_read_vref_training the arrays dvw_min_byte0_table and
dvw_min_byte1_table have 128 elements per channel. The variable
vref_stop_index is limited to be a maximum of 128. This means that the
index used to access the arrays must use a test of '< vref_stop_index'
rather than '<= vref_stop_index' in order to prevent out of bounds
accesses to the arrays.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Tested-by: Marek Vasut <marek.vasut+renesas@mailbox.org>