[PATCH] powerpc/fadump: reject empty bootargs_append writes

[Pengpeng Hou]

Hi Sourabh, Christophe,

Thanks for checking this.

I rechecked the current sysfs write path and I no longer think this
patch is valid. sysfs_kf_write() returns 0 before calling ->store() when
count is 0, so I do not have a path that reaches bootargs_append_store()
with count == 0.

Also, if such a path did exist, returning 0 would be the right behavior
for an empty write, not -EINVAL.

I'll drop this patch.

Thanks,
Pengpeng