ARM: ecard: ensure fake vma vm_flags is setup

Our TLB ops want to check the vma vm_flags to find out whether the
mapping is executable.  However, we leave this uninitialized in
ecard.c.  Initialize it with an appropriate value.

Reported-by: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>