[NDS32] Add constraint for lwi45.fe instruction.

[NDS32] Add constraint for lwi45.fe instruction.

gcc/
	* config/nds32/constraints.md (Ufe): New memory constraint.
	* config/nds32/nds32-md-auxiliary.c (nds32_mem_format,
	nds32_output_16bit_load): Consider r8 register for lwi45.fe format.
	* config/nds32/nds32.c (nds32_print_operand): Output lwi45.fe
	operands.
	* config/nds32/nds32.h (nds32_16bit_address_type): Add ADDRESS_R8_IMM7U.
	* config/nds32/nds32.md (*mov<mode>): Adjust pattern.

Co-Authored-By: Kito Cheng <kito.cheng@gmail.com>
From-SVN: r259121