tracing: Fix compilation warning on arm32

On arm32, size_t is defined to be unsigned int, while PAGE_SIZE is
unsigned long. This hence triggers a compilation warning as min()
asserts the type of two operands to be equal. Casting PAGE_SIZE to size_t
solves this issue and works on other target architectures as well.

Compilation warning details:

kernel/trace/trace.c: In function 'tracing_splice_read_pipe':
./include/linux/minmax.h:20:28: warning: comparison of distinct pointer types lacks a cast
  (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                            ^
./include/linux/minmax.h:26:4: note: in expansion of macro '__typecheck'
   (__typecheck(x, y) && __no_side_effects(x, y))
    ^~~~~~~~~~~

...

kernel/trace/trace.c:6771:8: note: in expansion of macro 'min'
        min((size_t)trace_seq_used(&iter->seq),
        ^~~

Cc: [email protected]
Link: https://lore.kernel.org/[email protected]
Fixes: f5178c4 ("tracing: Fix oob write in trace_seq_to_buffer()")
Reviewed-by: Jeongjun Park <[email protected]>
Signed-off-by: Pan Taixi <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: Pan Taixi

kernel/trace/trace.c

@@ -6891,7 +6891,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
 					  min((size_t)trace_seq_used(&iter->seq),
-						  PAGE_SIZE));
+						  (size_t)PAGE_SIZE));
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;