GDB: Remove Linux core PRPSINFO note writer override

GDB: Remove Linux core PRPSINFO note writer override

Revert parts of commit b3ac9c77560a ("Put more info in NT_PRPSINFO Linux
notes"), <https://sourceware.org/ml/binutils/2013-02/msg00024.html>, and
remove support for a Linux core PRPSINFO note writer override, now that
all variants are handled automatically within BFD itself.

	gdb/
	* linux-tdep.c (linux_make_corefile_notes): Remove call to
	`gdbarch_elfcore_write_linux_prpsinfo'.
	* gdbarch.sh (elfcore_write_linux_prpsinfo): Remove architecture
	method.
	(elf_internal_linux_prpsinfo): Remove declaration.
	* gdbarch.h: Regenerate.
	* gdbarch.c: Regenerate.