ntb: ntb_hw_switchtec: Fix array-index-out-of-bounds access

In the Linux kernel, the following vulnerability has been resolved:

ntb: ntb_hw_switchtec: Fix array-index-out-of-bounds access

Number of MW LUTs depends on NTB configuration and can be set to MAX_MWS,

This patch protects against invalid index out of bounds access to mw_sizes

When invalid access print message to user that configuration is not valid.