Don't call gdbarch_pseudo_register_read_value in jit.c
    
    gdbarch_pseudo_register_read_value is not implemented in every gdbarch, so
    the predicate gdbarch_pseudo_register_read_value_p is needed before
    calling it.  However, there is no such guard in jit_frame_prev_register, I
    am wondering how does jit work on the arch without having gdbarch method
    pseudo_register_read_value.
    
    The proper way to get register value is to call cooked_read, and then
    create the value object from the buffer.
    
    gdb:
    
    2018-01-22  Yao Qi  <yao.qi@linaro.org>
    
    	* jit.c (jit_frame_prev_register): Call regcache::cooked_read
    	instead of gdbarch_pseudo_register_read_value.