[efi] Fix operator precedence in autoexec network download

The != operator has higher precedence than = in C, so the expressions:

  rc = imgacquire ( ..., image ) != 0

are parsed as:

  rc = ( imgacquire ( ..., image ) != 0 )

This assigns the boolean result (0 or 1) to rc instead of the actual
return code from imgacquire().  As a result, strerror(rc) reports an
incorrect error message when debugging is enabled.

Add parentheses around each assignment to ensure rc captures the
actual return value, matching the pattern already used in
efi_autoexec_filesystem() within the same file.

Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Author: Huzaifa Ali Zar

src/interface/efi/efi_autoexec.c

@@ -132,10 +132,10 @@ static int efi_autoexec_network ( EFI_HANDLE handle, struct image **image ) {
 	}
 
 	/* Attempt download from current working URI, then from root */
-	if ( ( rc = imgacquire ( EFI_AUTOEXEC_NAME, EFI_AUTOEXEC_TIMEOUT,
-				 image ) != 0 ) &&
-	     ( rc = imgacquire ( "/" EFI_AUTOEXEC_NAME, EFI_AUTOEXEC_TIMEOUT,
-				 image ) != 0 ) ) {
+	if ( ( ( rc = imgacquire ( EFI_AUTOEXEC_NAME, EFI_AUTOEXEC_TIMEOUT,
+				   image ) ) != 0 ) &&
+	     ( ( rc = imgacquire ( "/" EFI_AUTOEXEC_NAME, EFI_AUTOEXEC_TIMEOUT,
+				   image ) ) != 0 ) ) {
 		DBGC ( device, "EFI %s could not download [/]%s: %s\n",
 		       efi_handle_name ( device ), EFI_AUTOEXEC_NAME,
 		       strerror ( rc ) );