tpm.c: fix crash during device removal

The clean up procedure now uses platform device "release" callback to
handle memory clean up.  For this purpose "release" function callback was
added to struct tpm_vendor_specific, so hw device driver provider can get
called when it is safe to remove all allocated resources.

This is supposed to fix a bug in device removal, where device while in
receive function (waiting on timeout) was prone to segfault, if the
tpm_chip struct was unallocated before the timeout expired (in
tpm_remove_hardware).

Acked-by: Marcel Selhorst <tpm@selhorst.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/tpm/tpm.h

@@ -74,6 +74,7 @@ struct tpm_vendor_specific {
 	int (*send) (struct tpm_chip *, u8 *, size_t);
 	void (*cancel) (struct tpm_chip *);
 	u8 (*status) (struct tpm_chip *);
+	void (*release) (struct device *);
 	struct miscdevice miscdev;
 	struct attribute_group *attr_group;
 	struct list_head list;
@@ -106,6 +107,7 @@ struct tpm_chip {
 	struct dentry **bios_dir;
 
 	struct list_head list;
+	void (*release) (struct device *);
 };
 
 #define to_tpm_chip(n) container_of(n, struct tpm_chip, vendor)