i#7046 memory dump: add missing pstate value to aarch64 user_regs_struct.

[ivankyluk]

#7088 missed the pstate when copying the register values from priv_mcontext_t to user_regs_struct.

The user_regs_struct has the follow fields:

struct user_regs_struct { unsigned long long regs[31]; unsigned long long sp; unsigned long long pc; unsigned long long pstate; };

for Aarch64. The rest of the fields have already been copied.

Issue: #7046