tpm: move TPM_DIGEST_SIZE defintion

IMA requires access to TPM_DIGEST_SIZE definition.  This patch
moves the definition to <linux/tpm.h>.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index fcb627f..9a9051b 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -22,6 +22,8 @@
 #ifndef __LINUX_TPM_H__
 #define __LINUX_TPM_H__
 
+#define TPM_DIGEST_SIZE 20	/* Max TPM v1.2 PCR size */
+
 /*
  * Chip num is this value or a valid tpm idx
  */