PM / sleep: declare __tracedata symbols as char[] rather than char

Accessing more than one byte from a symbol declared simply 'char' is undefined
behavior, as reported by UBSAN:

	UBSAN: Undefined behaviour in drivers/base/power/trace.c:178:18
	load of address ffffffff8203fc78 with insufficient space
	for an object of type 'char'

Avoid this by declaring the symbols as arrays.

Signed-off-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>