hw/char/pl011: Simplify a bit pl011_can_receive()

Introduce 'fifo_depth' and 'fifo_available' local variables
to better express the 'r' variable use.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Luc Michel <luc.michel@amd.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250220092903.3726-3-philmd@linaro.org>
diff --git a/hw/char/pl011.c b/hw/char/pl011.c
index 12a2d4b..5bb83c5 100644
--- a/hw/char/pl011.c
+++ b/hw/char/pl011.c
@@ -486,7 +486,9 @@
 static int pl011_can_receive(void *opaque)
 {
     PL011State *s = (PL011State *)opaque;
-    int r;
+    unsigned fifo_depth = pl011_get_fifo_depth(s);
+    unsigned fifo_available = fifo_depth - s->read_count;
+    int r = fifo_available ? 1 : 0;
 
     if (!(s->cr & CR_UARTEN)) {
         qemu_log_mask(LOG_GUEST_ERROR,
@@ -496,7 +498,6 @@
         qemu_log_mask(LOG_GUEST_ERROR,
                       "PL011 receiving data on disabled RX UART\n");
     }
-    r = s->read_count < pl011_get_fifo_depth(s);
     trace_pl011_can_receive(s->lcr, s->read_count, r);
     return r;
 }