um: remove uml initcalls

__uml_initcall() is not used and .uml.initcall.init section is empty:

$ grep -r '__uml_initcall('
arch/um/include/shared/init.h:#define __uml_initcall(fn)	\
$ readelf -s ../umobj/linux | grep __uml_initcall
 23214: 00000000603b75d8     0 NOTYPE  GLOBAL DEFAULT   32 __uml_initcall_start
 25337: 00000000603b75d8     0 NOTYPE  GLOBAL DEFAULT   32 __uml_initcall_end

So it is unnecessary.

Signed-off-by: Alexander Pateenok <pateenoc@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>