mm/vmalloc.c: optimize to reduce arguments of alloc_vmap_area()

If called by __get_vm_area_node(), by open coding the field assignments of
'struct vm_struct *vm', and move the vm->flags and vm->caller assignments
into __get_vm_area_node(), the passed in arguments 'flags' and 'caller'
can be removed.

This alleviates overloaded arguments passed in for alloc_vmap_area().

Link: https://lkml.kernel.org/r/20240309044454.648888-1-bhe@redhat.com


Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>