CVE-2025-40193 xtensa: simdisk: add input size check in proc_write_simdisk

In the Linux kernel, the following vulnerability has been resolved: xtensa: simdisk: add input size check in procwritesimdisk A malicious user could pass an arbitrarily bad value to memdupusernul, potentially causing kernel crash. This follows the same pattern as commit ee76746387f6 "netdevsim:...