x86/boot: Clean up whitespace in a20.c

Remove trailing whitespace on empty lines.

No functional changes.

  [ bp: Massage commit message. ]

Signed-off-by: Harry Fellowes <harryfellowes1@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20250825192832.6444-3-harryfellowes1@gmail.com

Author: zfellowes

arch/x86/boot/a20.c

@@ -135,29 +135,29 @@ int enable_a20(void)
 		  (legacy free, etc.) */
 	       if (a20_test_short())
 		       return 0;
-	       
+
 	       /* Next, try the BIOS (INT 0x15, AX=0x2401) */
 	       enable_a20_bios();
 	       if (a20_test_short())
 		       return 0;
-	       
+
 	       /* Try enabling A20 through the keyboard controller */
 	       kbc_err = empty_8042();
 
 	       if (a20_test_short())
 		       return 0; /* BIOS worked, but with delayed reaction */
-	
+
 	       if (!kbc_err) {
 		       enable_a20_kbc();
 		       if (a20_test_long())
 			       return 0;
 	       }
-	       
+
 	       /* Finally, try enabling the "fast A20 gate" */
 	       enable_a20_fast();
 	       if (a20_test_long())
 		       return 0;
        }
-       
+
        return -1;
 }