[otp_ctrl] fix part_unbuf otp_size_o selection

As Michael suggested in issue #4381, this PR implemented the fix for
otp_size_o when SW partition uses DAI to write digest.

Signed-off-by: Cindy Chen <chencindy@google.com>

hw/ip/otp_ctrl/rtl/otp_ctrl_part_unbuf.sv

diff --git a/hw/ip/otp_ctrl/rtl/otp_ctrl_part_unbuf.sv b/hw/ip/otp_ctrl/rtl/otp_ctrl_part_unbuf.sv
index 5070a7c..28fb8d8 100644
--- a/hw/ip/otp_ctrl/rtl/otp_ctrl_part_unbuf.sv
+++ b/hw/ip/otp_ctrl/rtl/otp_ctrl_part_unbuf.sv
@@ -286,8 +286,8 @@
                                                      {tlul_addr_q, 2'b00} >> OtpAddrShift;
   // Request 32bit except in case of the digest.
   assign otp_size_o = (otp_addr_sel == DigestAddr) ?
-                      OtpSizeWidth'(unsigned'(32 / OtpWidth - 1)) :
-                      OtpSizeWidth'(unsigned'(ScrmblBlockWidth / OtpWidth - 1));
+                      OtpSizeWidth'(unsigned'(ScrmblBlockWidth / OtpWidth - 1)) :
+                      OtpSizeWidth'(unsigned'(32 / OtpWidth - 1));
 
   ////////////////
   // Digest Reg //