mmc: use correct unregister function for led trigger
mmc: use correct unregister function for led trigger

We register a simple trigger so make sure we use the corresponding
unregister function.

(Also means we get a dummy function when triggers aren't compiled in)

Signed-off-by: Pierre Ossman <8b64f2aeec7ea42cd6838e5b2901f7aa61dfa5d4@drzeus.cx>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs