hwrng: core - Simplify RNG switching from sysfs

If we attempt to use sysfs to change the current RNG in the usual
way i.e. issuing something like:

`echo 8a8a000.rng > /sys/devices/virtual/misc/hw_random/rng_current`

... it will fail because the code doesn't currently take the '\n'
into consideration.  Well, now it does.
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Acked-by: NPeter Korsgaard <peter@korsgaard.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/core.c

@@ -323,7 +323,7 @@ static ssize_t hwrng_attr_current_store(struct device *dev,
 		return -ERESTARTSYS;
 	err = -ENODEV;
 	list_for_each_entry(rng, &rng_list, list) {
-		if (strcmp(rng->name, buf) == 0) {
+		if (sysfs_streq(rng->name, buf)) {
 			err = 0;
 			if (rng != current_rng)
 				err = set_current_rng(rng);