drm/amd/display: Validate GPIO pin LUT table size before iterating

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Validate GPIO pin LUT table size before iterating [Why&How] The GPIO pin table parsers in get_gpio_i2c_info() and bios_parser_get_gpio_pin_info() derive an element count from the VBIOS table_header.structuresize field, then iterate over gpio_pin[] entries. However, GET_IMAGE() only validates that the table header itself fits within the BIOS image. If the VBIOS reports a structuresize larger than the actual mapped data, the loop reads past the end of the BIOS image, causing an out-of-bounds read. Fix this by calling bios_get_image() to validate that the full claimed structuresize is accessible within the BIOS image before entering the loop in both functions. (cherry picked from commit ba5e95b43b773ae1bf1f66ee6b31eb774e65afe3)