Fix typo of MBEDTLS_TLS13_SIG_IGNATURE_RSA_PSS_RSAE_SHA256

Summary: Fix the following compiler error.

/home/lhuang04/upstream/library/ssl_tls.c:7320:5: error: ‘MBEDTLS_TLS13_SIG_IGNATURE_RSA_PSS_RSAE_SHA256’ undeclared here (not in a function)
     MBEDTLS_TLS13_SIG_IGNATURE_RSA_PSS_RSAE_SHA256,
     ^
make[2]: *** [library/CMakeFiles/mbedtls.dir/ssl_tls.c.o] Error 1
make[2]: *** Waiting for unfinished jobs....

Test Plan: Turn on MBEDTLS_X509_RSASSA_PSS_SUPPORT by the following patch and build

diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index ffaa4e3ea..58b54fd18 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -1882,7 +1882,7 @@
  *
  * Comment this macro to disallow using RSASSA-PSS in certificates.
  */
-//#define MBEDTLS_X509_RSASSA_PSS_SUPPORT
+#define MBEDTLS_X509_RSASSA_PSS_SUPPORT
 /* \} name SECTION: mbed TLS feature support */

 /**
@@ -2757,7 +2757,7 @@
  *
  * Requires: MBEDTLS_BIGNUM_C, MBEDTLS_OID_C
  */
-//#define MBEDTLS_RSA_C
+#define MBEDTLS_RSA_C

 /**
  * \def MBEDTLS_SHA1_C

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hannestschofenig / mbedtls