fsdax: remove redundant variable 'error'

fsdax: remove redundant variable 'error'

The variable 'error' is being assigned a value that is never read,
the assignment and the variable and redundant and can be removed.
Cleans up clang scan build warning:

fs/dax.c:1880:10: warning: Although the value stored to 'error' is
used in the enclosing expression, the value is never actually read
from 'error' [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20230621130256.2676126-1-colin.i.king@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>