riscv: kprobes: convert one final __ASSEMBLY__ to __ASSEMBLER__

Per the reasoning in commit f811f58 ("riscv: Replace __ASSEMBLY__
with __ASSEMBLER__ in non-uapi headers"), convert one last remaining
instance of __ASSEMBLY__ in the arch/riscv kprobes code.  This entered
the tree from patches that were sent before Thomas' changes; and when
I reviewed the kprobes patches before queuing them, I missed this
instance.

Cc: Nam Cao <namcao@linutronix.dev>
Cc: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/linux-riscv/16b74b63-f223-4f0b-b6e5-31cea5e620b4@redhat.com/
Link: https://lore.kernel.org/linux-riscv/20250606070952.498274-1-thuth@redhat.com/
Signed-off-by: Paul Walmsley <pjw@kernel.org>

Author: Paul Walmsley

arch/riscv/kernel/tests/kprobes/test-kprobes.h

@@ -11,14 +11,14 @@
 #define KPROBE_TEST_MAGIC_LOWER    0x0000babe
 #define KPROBE_TEST_MAGIC_UPPER    0xcafe0000
 
-#ifndef __ASSEMBLY__
+#ifndef __ASSEMBLER__
 
 /* array of addresses to install kprobes */
 extern void *test_kprobes_addresses[];
 
 /* array of functions that return KPROBE_TEST_MAGIC */
 extern long (*test_kprobes_functions[])(void);
 
-#endif /* __ASSEMBLY__ */
+#endif /* __ASSEMBLER__ */
 
 #endif /* TEST_KPROBES_H */