[nvptx] Fix some missing mode warnings in nvptx.md

[nvptx] Fix some missing mode warnings in nvptx.md

Fix these warnings:
...
gcc/config/nvptx/nvptx.md:748:1: warning: operand 0 missing mode?
gcc/config/nvptx/nvptx.md:757:1: warning: operand 1 missing mode?
gcc/config/nvptx/nvptx.md:1514:1: warning: source missing a mode?
...

Build and reg-tested on x86_64 with nvptx accelerator.

2019-06-17  Tom de Vries  <tdevries@suse.de>

	* config/nvptx/nvptx.md (define_insn "call_insn"): Rename to ...
	(define_insn "call_insn_<mode>"): ... this.  Use P iterator on
	match_operand 0.
	(define_insn "call_value_insn"): Rename to ...
	(define_insn "call_value_insn_<mode>"): this.  Use P iterator on
	match_operand 0.
	(define_insn "nvptx_red_partition"): Set unspec_volatile result mode to
	DI.

From-SVN: r272365