init: Simplify symbol name generated by DECLARE_DEVICE_INIT_CONFIG()

Gets rid of the trailing initialization level character from the
name of the device variable generated by the macro, since it serves
no useful purpose. (The linker scripts place the various initialization
sections in ascending order based on the name of the section, so there
is no need to embed the initialization level in the variable name itself.)

Change-Id: I56bb79a513b8f77fb1f3fbaccec14454c2520772
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>