kvm: arm64: use BUG() instead of BUG_ON(1)

The BUG_ON() macro adds a little bit of complexity over BUG(), and in
some cases this ends up confusing the compiler's control flow analysis
in a way that results in a warning. This one now shows up with clang-21:

arch/arm64/kvm/vgic/vgic-mmio.c:1094:3: error: variable 'len' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
 1094 |                 BUG_ON(1);

Change both instances of BUG_ON(1) to a plain BUG() in the arm64 kvm
code, to avoid the false-positive warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20250807072132.4170088-1-arnd@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: arndb

arch/arm64/kvm/hyp/nvhe/list_debug.c

@@ -17,7 +17,7 @@ static inline __must_check bool nvhe_check_data_corruption(bool v)
 		bool corruption = unlikely(condition);			 \
 		if (corruption) {					 \
 			if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \
-				BUG_ON(1);				 \
+				BUG();				 	 \
 			} else						 \
 				WARN_ON(1);				 \
 		}							 \

arch/arm64/kvm/vgic/vgic-mmio.c

@@ -1091,7 +1091,7 @@ int vgic_register_dist_iodev(struct kvm *kvm, gpa_t dist_base_address,
 		len = vgic_v3_init_dist_iodev(io_device);
 		break;
 	default:
-		BUG_ON(1);
+		BUG();
 	}
 
 	io_device->base_addr = dist_base_address;