ggml-hexagon: add hex_supported_buffer for better buffer supported check

[chraac]

Description

This PR introduces a new hex_supported_buffer function to improve buffer support checking in the ggml-hexagon backend.

Changes

• Refactored buffer support checking: Added a dedicated hex_supported_buffer() function to centralize and improve the logic for determining whether a buffer is supported by the Hexagon backend

Benefits

• Better maintainability: Centralized buffer support logic makes the codebase easier to maintain and update
• Improved clarity: The new function provides a clearer and more explicit way to check buffer compatibility
• Reduced duplication: Eliminates redundant buffer checking code throughout the Hexagon backend

[chraac]

Hi @max-krasnyansky and @lhez,

What do you think about introducing the hex_supported_buffer() template helper function to minimize code duplication?
This should make it easier to add new ops in the future by providing a consistent, reusable buffer support check. Open to feedback!