LoongArch: Organize the code related to split move and merge the same functions.

LoongArch: Organize the code related to split move and merge the same functions.

gcc/ChangeLog:

	* config/loongarch/loongarch-protos.h
	(loongarch_split_128bit_move): Delete.
	(loongarch_split_128bit_move_p): Delete.
	(loongarch_split_256bit_move): Delete.
	(loongarch_split_256bit_move_p): Delete.
	(loongarch_split_vector_move): Add a function declaration.
	* config/loongarch/loongarch.cc
	(loongarch_vector_costs::finish_cost): Adjust the code
	formatting.
	(loongarch_split_vector_move_p): Merge
	loongarch_split_128bit_move_p and loongarch_split_256bit_move_p.
	(loongarch_split_move_p): Merge code.
	(loongarch_split_move): Likewise.
	(loongarch_split_128bit_move_p): Delete.
	(loongarch_split_256bit_move_p): Delete.
	(loongarch_split_128bit_move): Delete.
	(loongarch_split_vector_move): Merge loongarch_split_128bit_move
	and loongarch_split_256bit_move.
	(loongarch_split_256bit_move): Delete.
	(loongarch_global_init): Remove the extra semicolon at the
	end of the function.
	* config/loongarch/loongarch.md (*movdf_softfloat):  Added a new
	condition TARGET_64BIT.