function_graph: Rename BYTE_NUMBER to CHAR_NUMBER in selftests

The function_graph selftests checks various size variables to pass from
the entry of the function to the exit. It tests 1, 2, 4 and 8 byte words.
The 1 byte macro was called BYTE_NUMBER but that is used in the sh
architecture: arch/sh/include/asm/bitops-op32.h

Just rename the macro to CHAR_NUMBER.

Link: https://lore.kernel.org/linux-trace-kernel/20240606081846.4cb82dc4@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 47c3c70a ("function_graph: Add selftest for passing local variables")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406061744.rZDXfRrG-lkp@intel.com/Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

kernel/trace/trace_selftest.c

@@ -758,7 +758,7 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
-#define BYTE_NUMBER 123
+#define CHAR_NUMBER 123
 #define SHORT_NUMBER 12345
 #define WORD_NUMBER 1234567890
 #define LONG_NUMBER 1234567890123456789LL
@@ -789,7 +789,7 @@ static __init int store_entry(struct ftrace_graph_ent *trace,
 
 	switch (size) {
 	case 1:
-		*(char *)p = BYTE_NUMBER;
+		*(char *)p = CHAR_NUMBER;
 		break;
 	case 2:
 		*(short *)p = SHORT_NUMBER;
@@ -830,7 +830,7 @@ static __init void store_return(struct ftrace_graph_ret *trace,
 
 	switch (fixture->store_size) {
 	case 1:
-		expect = BYTE_NUMBER;
+		expect = CHAR_NUMBER;
 		found = *(char *)p;
 		break;
 	case 2: