qemu/osdep: align memory allocations to 2M on RISC-V

Similar to other architectures (e.g., x86_64, aarch64), utilizing THP on RISC-V
KVM requires 2MiB-aligned memory blocks.

Signed-off-by: Xuemei Liu <liu.xuemei1@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20250924131803656Yqt9ZJKfevWkInaGppFdE@zte.com.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 1b38cb7..6de6c0c 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -561,7 +561,7 @@
 
 #if defined(__linux__) && \
     (defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
-     || defined(__powerpc64__))
+     || defined(__powerpc64__) || defined(__riscv))
    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
       Valgrind does not support alignments larger than 1 MiB,
       therefore we need special code which handles running on Valgrind. */