parisc: BTLB: Fix crash when setting up BTLB at CPU bringup

In the Linux kernel, the following vulnerability has been resolved: parisc: BTLB: Fix crash when setting up BTLB at CPU bringup When using hotplug and bringing up a 32-bit CPU, ask the firmware about the BTLB information to set up the static (block) TLB entries. For that write access to the static btlb_info struct is needed, but since it is marked __ro_after_init the kernel segfaults with missing write permissions. Fix the crash by dropping the __ro_after_init annotation.