seminaries/qtrvsim/uart-echo-irq: minor update to build by internal assembler

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

seminaries/qtrvsim/uart-echo-irq/uart-echo-irq.S

@@ -85,8 +85,8 @@ skip:
 loop:
         csrrs t1, mepc, zero // check
         sw      t1, SPILED_REG_LED_LINE_o(a0)
-        srl     t2, t0, 31
-        sll     t0, t0, 1
+        srli    t2, t0, 31
+        slli    t0, t0, 1
         or      t0, t0, t2
         lw      t2, SPILED_REG_KNOBS_8BIT_o(a0)
         sw      t2, SPILED_REG_LED_RGB1_o(a0)
@@ -117,11 +117,11 @@ ret_from_exception:
 
 handle_irq:                                     // t0 mcause
         slli    t0, t0, 2                       // shift out sign, left sources * 4
-        /* the t0 would be used to point into irq handlers table */
-        /* check only for UART RX interupt for simplicity 8 */ 
+        // the t0 would be used to point into irq handlers table
+        // check only for UART RX interupt for simplicity
         addi    a0, zero, 16 * 4                // UART RX is the first platform irq
         beq     t0, a0, handle_uart_rx_irq      // it is UART RX
-        /* mask out unknown sources */
+        // mask out unknown sources
         srli    t0, t0, 2                       // make t0 back simple source index
         addi    a0, zero, 1
         sll     a0, a0, t0                      // generate bit mask for source