mfd: Introduce missing kfree in 88pm860x probe routine

Error handling code following a kzalloc should free the allocated data.  At
this point, chip has been allocated and some fields have been initialized,
but it has not been stored anywhere, so it should be freed before leaving
the function.

A simplified version of the semantic match that finds the problem is as
follows: (http://coccinelle.lip6.fr

)

// <smpl>
@r exists@
local idexpression x;
statement S;
identifier f1;
position p1,p2;
expression *ptr != NULL;
@@

x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...x...+> }
x->f1
...>
(
 return \(0\|<+...x...+>\|ptr\);
|
 return@p2 ...;
)

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>