PR32698, potential null pointer dereference in tekhex.c

	PR 32698
	* tekhex.c (find_chunk): Remove unnecessary casts.
	(insert_byte): Check and return status from find_chunk.
	(move_section_contents): Likewise.
	(tekhex_get_section_contents, tekhex_set_arch_mach): Return
	status from move_section_contents.
	(first_phase): Check and return status from first_phase.