Documentation/powerpc: Ultravisor API

[Julia Lawall]

The file Documentation/powerpc/ultravisor.rst contains:

    Only valid value(s) in ``flags`` are:

        * H_PAGE_IN_SHARED which indicates that the page is to be shared
	  with the Ultravisor.

        * H_PAGE_IN_NONSHARED indicates that the UV is not anymore
          interested in the page. Applicable if the page is a shared page.

The flag H_PAGE_IN_SHARED exists in the Linux kernel
(arch/powerpc/include/asm/hvcall.h), but the flag H_PAGE_IN_NONSHARED does
not.  Should the documentation be changed in some way?

julia