spi: altera_spi: Use BIT macro

Replace numerical bit shift with BIT macro
in altera_spi

:%s/(1 << nr)/BIT(nr)/g
where nr = 0, 1, 2 .... 31

Cc: Marek Vasut <marex@denx.de>
Acked-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>