Bluetooth: bpa10x: fix BT_HCIUART dependency

Bluetooth: bpa10x: fix BT_HCIUART dependency

The change to bpa10x to use the h4_recv_buf helper added a dependency
on BT_HCIUART. This was incorrectly added to Kconfig by adding a
'select' statement, which now in turn causes build failures
when CONFIG_TTY is not set:

warning: (BT_HCIBPA10X) selects BT_HCIUART which has unmet direct dependencies (NET && BT && TTY)
vers/built-in.o: In function `hci_uart_tty_receive':
fpga-mgr.c:(.text+0x282824): undefined reference to `tty_unthrottle'
drivers/built-in.o: In function `hci_uart_tty_ioctl':
fpga-mgr.c:(.text+0x282aa0): undefined reference to `n_tty_ioctl_helper'
drivers/built-in.o: In function `hci_uart_flush':

This replaces the 'select BT_HCIUART' dependency with 'depends on', which
does not have this kind of problem. Alternatively, one could add 'depends
on TTY', but avoiding 'select' on user-visible options is generally the
preferred choice as that does not introduce the potential for dependency
loops or incomplete dependency chains.

Fixes: 91489919247a ("Bluetooth: bpa10x: Fix missing BT_HCIUART dependency")
Fixes: 943cc592195e ("Bluetooth: bpa10x: Use h4_recv_buf helper for frame reassembly")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>