staging: fbtft: fb_tinylcd: replace udelay() with fsleep()

staging: fbtft: fb_tinylcd: replace udelay() with fsleep()

fsleep() is the preferred modern API for flexible sleeping as it
automatically selects the best sleep mechanism based on the duration.
Replace udelay() with fsleep() to improve power efficiency.

init_display() is a driver initialization callback which runs in
sleeping context, so fsleep() is safe to use here.

Signed-off-by: Tomasz Unger <tomasz.unger@yahoo.pl>
Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Link: https://patch.msgid.link/20260219142942.74087-1-tomasz.unger@yahoo.pl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>