tests: drivers: uart: Re-enabling some tests on nrf52_bsim

Tests which were using the new nordic UART shim where failing
on the bsim targets. They are now fixed and tests can be
re-enabled.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
(cherry picked from commit 362389ee170115149fad78090f72eed80486f6c3)
diff --git a/tests/drivers/uart/uart_async_api/testcase.yaml b/tests/drivers/uart/uart_async_api/testcase.yaml
index 8d53d93..46de733 100644
--- a/tests/drivers/uart/uart_async_api/testcase.yaml
+++ b/tests/drivers/uart/uart_async_api/testcase.yaml
@@ -34,7 +34,6 @@
     depends_on: gpio
     extra_configs:
       - CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=n
-    tags: bsim_skip_CI
   drivers.uart.async_api.nrf_uart:
     filter: CONFIG_SERIAL_SUPPORT_ASYNC
     harness: ztest
diff --git a/tests/drivers/uart/uart_mix_fifo_poll/testcase.yaml b/tests/drivers/uart/uart_mix_fifo_poll/testcase.yaml
index ccfdd1a..026b609 100644
--- a/tests/drivers/uart/uart_mix_fifo_poll/testcase.yaml
+++ b/tests/drivers/uart/uart_mix_fifo_poll/testcase.yaml
@@ -20,7 +20,6 @@
       - CONFIG_UART_ASYNC_API=n
       - CONFIG_UART_0_ENHANCED_POLL_OUT=n
       - CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=n
-    tags: bsim_skip_CI
 
   drivers.uart.uart_mix_poll_fifo:
     extra_configs:
@@ -28,7 +27,6 @@
       - CONFIG_UART_0_INTERRUPT_DRIVEN=y
       - CONFIG_UART_0_ENHANCED_POLL_OUT=n
       - CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=n
-    tags: bsim_skip_CI
 
   drivers.uart.uart_mix_poll_async_api:
     extra_configs:
@@ -37,7 +35,6 @@
       - CONFIG_UART_0_ASYNC=y
       - CONFIG_UART_0_ENHANCED_POLL_OUT=n
       - CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=n
-    tags: bsim_skip_CI
 
   drivers.uart.uart_mix_poll_async_api_const:
     extra_args: TEST_CONST_BUFFER=1