target/ppc: Remove `NB_MMU_MODES` define

Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230306175230.7110-16-anjo@rev.ng>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/ppc/cpu-param.h

@@ -32,6 +32,5 @@
 # define TARGET_VIRT_ADDR_SPACE_BITS 32
 #endif
 #define TARGET_PAGE_BITS 12
-#define NB_MMU_MODES 10
 
 #endif