mm: fix ambiguous comments for better code readability

commit 552657b7b3343851916fde7e4fd6bfb6516d2bcb upstream.

The parameter of remap_pfn_range() @pfn passed from the caller is actually
a page-frame number converted by corresponding physical address of kernel
memory, the original comment is ambiguous that may mislead the users.

Meanwhile, there is an ambiguous typo "VMM" in the comment of
vm_area_struct.  So fixing them will make the code more readable.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1583026921-15279-1-git-send-email-qiwuchen55@gmail.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Harshvardhan Jha <harshvardhan.j.jha@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>