mfd: macsmc: add new __SMC_KEY macro

When using the _SMC_KEY macro in switch/case statements, GCC 15.2.1 errors
out with 'case label does not reduce to an integer constant'. Introduce
a new __SMC_KEY macro that can be used instead.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>

Author: chadmed

include/linux/mfd/macsmc.h

@@ -41,6 +41,7 @@ typedef u32 smc_key;
  */
 #define SMC_KEY(s) (smc_key)(_SMC_KEY(#s))
 #define _SMC_KEY(s) (((s)[0] << 24) | ((s)[1] << 16) | ((s)[2] << 8) | (s)[3])
+#define __SMC_KEY(a, b, c, d) (((u32)(a) << 24) | ((u32)(b) << 16) | ((u32)(c) << 8) | ((u32)(d)))
 
 #define APPLE_SMC_READABLE BIT(7)
 #define APPLE_SMC_WRITABLE BIT(6)