[nrf noup] boot: zephyr: Surpress bootutil_decode_sig warning

nrf-squash! [nrf noup] boot: Add shared crypto for ECDSA and SHA

If ASN1 was not enabled (in case of PSA crypto) a "defined but
not used" warning was issued.
This changes could not be placed in upstream as the line was
modified by commit e3d6091

Signed-off-by: Artur Hadasz <[email protected]>

Author: ahasztag

boot/bootutil/include/bootutil/crypto/ecdsa.h

@@ -134,6 +134,7 @@ static int bootutil_import_key(uint8_t **cp, uint8_t *end)
 }
 #endif /* (MCUBOOT_USE_TINYCRYPT || MCUBOOT_USE_MBED_TLS || MCUBOOT_USE_CC310) && !MCUBOOT_USE_PSA_CRYPTO */
 
+#ifndef MCUBOOT_USE_PSA_CRYPTO
 /*
  * cp points to ASN1 string containing an integer.
  * Verify the tag, and that the length is 32 bytes. Helper function.
@@ -183,6 +184,7 @@ static int bootutil_decode_sig(uint8_t signature[NUM_ECC_BYTES * 2], uint8_t *cp
     }
     return 0;
 }
+#endif /* !MCUBOOT_USE_PSA_CRYPTO */
 
 #if defined(MCUBOOT_USE_TINYCRYPT)
 typedef uintptr_t bootutil_ecdsa_context;