scripts: west_commands: runners: fix dt-flash handling in some runners

In minichlink and spi_burn, the script checks if dt_flash is True by
checking if the value is "y". But dt_flash is a boolean.
Fix these checks.

Also, when dt-flash is True, spi_burn calculate the address in a
convoluted way, by substrating CONFIG_FLASH_LOAD_OFFSET to
itself.
Simplify this computation.

Signed-off-by: Miguel Gazquez <miguel.gazquez@bootlin.com>

scripts/west_commands/runners/minichlink.py

@@ -57,7 +57,7 @@ class MiniChLinkBinaryRunner(ZephyrBinaryRunner):
             minichlink=args.minichlink,
             erase=args.erase,
             reset=args.reset,
-            dt_flash=(args.dt_flash == "y"),
+            dt_flash=args.dt_flash,
             terminal=args.terminal,
         )
 

scripts/west_commands/runners/spi_burn.py

@@ -56,11 +56,14 @@ class SpiBurnBinaryRunner(ZephyrBinaryRunner):
             iceman  = 'ICEman'
 
         # Get flash address offset
-        if args.dt_flash == 'y':
+        if args.dt_flash:
             build_conf = BuildConfiguration(cfg.build_dir)
-            address = hex(
-                cls.get_flash_address(args, build_conf) - build_conf['CONFIG_FLASH_BASE_ADDRESS']
-            )
+
+            if build_conf.getboolean('CONFIG_HAS_FLASH_LOAD_OFFSET'):
+                address = hex(build_conf['CONFIG_FLASH_LOAD_OFFSET'])
+            else:
+                address = '0x0'
+
         else:
             address = args.addr