ext: oberon: Remove redefinition ECC_MAX_CURVE_BITS

This removes the redefinition of the define
PSA_VENDOR_ECC_MAX_CURVE_BITS which we will set in our configuration
file.

Ref: NCSDK-12898

This matches commit "[nrf noup] Remove redefinition ECC_MAX_CURVE_BITS"
applied to the sdk-mbedtls repository.

Signed-off-by: Joakim Andersson <joakim.andersson@nordicsemi.no>

ext/oberon/psa/core/include/psa/crypto_sizes.h

@@ -196,6 +196,8 @@
 
 /* The maximum size of an ECC key on this implementation, in bits.
  * This is a vendor-specific macro. */
+#ifndef PSA_VENDOR_ECC_MAX_CURVE_BITS
+
 #if defined(PSA_WANT_ECC_SECP_R1_521)           /*!!OM*/
 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 521
 #elif defined(PSA_WANT_ECC_BRAINPOOL_P_R1_512)
@@ -230,6 +232,8 @@
 #define PSA_VENDOR_ECC_MAX_CURVE_BITS 0
 #endif
 
+#endif
+
 /** This macro returns the maximum supported length of the PSK for the
  * TLS-1.2 PSK-to-MS key derivation
  * (#PSA_ALG_TLS12_PSK_TO_MS(\c hash_alg)).