CVE-2026-72424: rtc: msc313: fix NULL deref in shared IRQ handler at probe

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

rtc: msc313: fix NULL deref in shared IRQ handler at probe

msc313rtcprobe() calls devmrequestirq() with IRQFSHARED and &pdev->dev as the cookie, but platformsetdrvdata() is only called later after the clock setup. With a shared IRQ line, another device on the same line can trigger the handler in that window. The handler does devgetdrvdata() on the cookie, gets NULL, and dereferences priv->rtcbase in interrupt context.

Pass priv as the cookie directly so the handler reads it from devid without the lookup, removing the dependency on probe order.