tpm_crb: ffa_tpm: fix/update comments describing the CRB over FFA ABI

-Fix the comment describing the 'start' function, which was a cut/paste
 mistake for a different function.

-The comment for DIRECT_REQ and DIRECT_RESP only mentioned AArch32
 and listed 32-bit function IDs.  Update to include 64-bit.

Signed-off-by: Stuart Yoder <stuart.yoder@arm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

Author: stuyod01

drivers/char/tpm/tpm_crb_ffa.c

@@ -38,9 +38,11 @@
  * messages.
  *
  * All requests with FFA_MSG_SEND_DIRECT_REQ and FFA_MSG_SEND_DIRECT_RESP
- * are using the AArch32 SMC calling convention with register usage as
- * defined in FF-A specification:
- * w0:    Function ID (0x8400006F or 0x84000070)
+ * are using the AArch32 or AArch64 SMC calling convention with register usage
+ * as defined in FF-A specification:
+ * w0:    Function ID
+ *          -for 32-bit: 0x8400006F or 0x84000070
+ *          -for 64-bit: 0xC400006F or 0xC4000070
  * w1:    Source/Destination IDs
  * w2:    Reserved (MBZ)
  * w3-w7: Implementation defined, free to be used below
@@ -68,7 +70,8 @@
 #define CRB_FFA_GET_INTERFACE_VERSION 0x0f000001
 
 /*
- * Return information on a given feature of the TPM service
+ * Notifies the TPM service that a TPM command or TPM locality request is
+ * ready to be processed, and allows the TPM service to process it.
  * Call register usage:
  * w3:    Not used (MBZ)
  * w4:    TPM service function ID, CRB_FFA_START