serial: uartlite: Use dynamic allocation for major number when uart ports > 4

serial: uartlite: Use dynamic allocation for major number when uart ports > 4

Device number 204 has a range of minors on major number.
uart_register_driver is failing due to lack of minor numbers
when more number of uart ports used. So, to avoid minor number
limitation on 204 major number use dynamic major allocation
when more than 4 uart ports used otherwise use static major
allocation.

https://docs.kernel.org/arch/arm/sa1100/serial_uart.html

Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Link: https://lore.kernel.org/r/20231116134003.3762725-3-manikanta.guntupalli@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>