dlm: remove __user conversion warnings

This patch avoids the following sparse warning:

fs/dlm/user.c:111:38: warning: incorrect type in assignment (different address spaces)
fs/dlm/user.c:111:38:    expected void [noderef] __user *castparam
fs/dlm/user.c:111:38:    got void *
fs/dlm/user.c:112:37: warning: incorrect type in assignment (different address spaces)
fs/dlm/user.c:112:37:    expected void [noderef] __user *castaddr
fs/dlm/user.c:112:37:    got void *
fs/dlm/user.c:113:38: warning: incorrect type in assignment (different address spaces)
fs/dlm/user.c:113:38:    expected void [noderef] __user *bastparam
fs/dlm/user.c:113:38:    got void *
fs/dlm/user.c:114:37: warning: incorrect type in assignment (different address spaces)
fs/dlm/user.c:114:37:    expected void [noderef] __user *bastaddr
fs/dlm/user.c:114:37:    got void *
fs/dlm/user.c:115:33: warning: incorrect type in assignment (different address spaces)
fs/dlm/user.c:115:33:    expected struct dlm_lksb [noderef] __user *lksb
fs/dlm/user.c:115:33:    got void *
fs/dlm/user.c:130:39: warning: cast removes address space '__user' of expression
fs/dlm/user.c:131:40: warning: cast removes address space '__user' of expression
fs/dlm/user.c:132:36: warning: cast removes address space '__user' of expression

So far I see there is no direct handling of copying a pointer value to
another pointer value. The handling only copies the actual pointer
address to a scalar type or vice versa. This should be okay because it
never handles dereferencing anything of those addresses in the kernel
space. To get rid of those warnings we doing some different casting
which results in no warnings in sparse or compiler.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>