* gdbarch.sh (read_sp): Remove.
* gdbarch.c, gdbarch.h: Regenerate.
* frame.c (frame_sp_unwind): Do not call TARGET_READ_SP.
* avr-tdep.c (avr_read_sp): Remove.
(avr_unwind_sp): New function.
(avr_gdbarch_init): Install unwind_sp instead of read_sp callback.
* mips-tdep.c (mips_read_sp): Remove.
(mips_unwind_sp): New function.
(mips_gdbarch_init): Install unwind_sp instead of read_sp callback.
* score-tdep.c (score_read_unsigned_register): Remove.
(score_read_sp): Remove.
(score_unwind_sp): New function.
(score_gdbarch_init): Install unwind_sp instead of read_sp callback.