package/azure-iot-sdk-c: drop custom install rules

Drop custom install rules which have been added since the addition of
the package in commit 2d837933 but are
now resulting in a broken installion

Fixes:
 - https://bugs.buildroot.org/show_bug.cgi?id=14636



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>