mmc-utils: One further optimization of trimming routine

The last change to the trimming routine made it more efficient,
however, we can even get rid of the memmove() as we leave the
function with strdup() anyway.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Avri Altman <avri.altman@wdc.com>
Link: https://lore.kernel.org/r/20210920194633.814-1-mhei@heimpold.de
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

lsmmc.c

@@ -393,10 +393,9 @@ char *read_file(char *name)
 		start++;
 		len--;
 	}
-	memmove(line, start, len);
-	line[len] = '\0';
 
-	return strdup(line);
+	start[len] = '\0';
+	return strdup(start);
 }
 
 /* Hexadecimal string parsing functions */