CVE-2026-93132: ACPI: RISC-V: Fix riscv_acpi_add_prt_dep() loop handling

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

ACPI: RISC-V: Fix riscvacpiaddprtdep() loop handling

The loop in riscvacpiaddprtdep() includes error conditions that are handled in a dubious - if not outright wrong - way, by continuining the loop (which skips and misses the entry pointer update to point to the next entry).

Rewrite the loop as a for loop (that handles the continuation correctly) and wrap the condition and update statements using helper functions to make it cleaner.