lib/string_helpers.c:string_get_size(): remove redundant prefixes

While commit 3c9f3681d0b4 ("[SCSI] lib: add generic helper to print
sizes rounded to the correct SI range") says that Z and Y are included
in preparation for 128 bit computers, they just waste .text currently.
If and when we get u128, string_get_size needs updating anyway (and ISO
needs to come up with four more prefixes).

Also there's no need to include and test for the NULL sentinel; once we
reach "E" size is at most 18. [The test is also wrong; it should be
units_str[units][i+1]; if we've reached NULL we're already doomed.]

Signed-off-by: Rasmus Villemoes <[e-mail]>
Cc: James Bottomley <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

lib/string_helpers.c

···
 		    char *buf, int len)
 {
 	static const char *const units_10[] = {
-		"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB", NULL
+		"B", "kB", "MB", "GB", "TB", "PB", "EB"
 	};
 	static const char *const units_2[] = {
-		"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB",
-		NULL
+		"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB"
 	};
 	static const char *const *const units_str[] = {
 		[STRING_UNITS_10] = units_10,
···
 	tmp[0] = '\0';
 	i = 0;
 	if (size >= divisor[units]) {
-		while (size >= divisor[units] && units_str[units][i]) {
+		while (size >= divisor[units]) {
 			remainder = do_div(size, divisor[units]);
 			i++;
 		}