gpio-mlxbf3: support valid mask

[Asmaa Mnebhi]

SRU Justification:

[Impact]

After syncing up the gpio-mlxbf3.c driver with the upstreamed version, we dropped the use of the valid_mask variable because kernels greater or equal to 6.2.0 dont need it.
This is no longer needed in kernel versions >= 6.2.0 because valid_mask is populated by core gpio code.
5.15 kernel doesnt support that feature so we still need to explicitly define valid_mask like we did before.
This doesnt impact the functionality of the GPIO driver but it is a security breach as it doesnt restrict the access to only gpios defined in the acpi table by valid_mask.

[Fix]

* define valid_mask and init_valid_mask

[Test Case]

* Make sure that the user (libgpiod) cannot access any other gpio besides 0->4 (gpiochip0) and 22-23 in gpiochip1.

[Regression Potential]

no known regression.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.15.0-1029.31 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-done-jammy-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-failed-jammy-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!