fdtget.c: Fix memory leak

CID 132823 (#1 of 1): Resource leak (RESOURCE_LEAK)
5. leaked_storage: Variable blob going out of scope leaks the storage it points to.

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>