Driving and dimming TFT LCD backlight
Since this question did not get any attention I am posting my own solution just in case.

The 5 LEDs in parallel can be treated as one, so I found nice single WLED driver chip MIC4801 that needs only one resistor to set current and supports up to 500kHz PWM control, which is on par with complicated DC injection into feedback line in the schematics suggested by the manufacturer.

Unfortunately, despite 0.13V dropout claimed by the datasheet, it was only able to supply 50 mA @ 2.8V to the LED when powered from 3.3V. However when powered from 5V it immediately settled at 100 mA @ 3.07V on the LED, which are spot-on display datasheet numbers.

I do have 5V available in the circuit, so this $0.80 solution was perfect for me, requiring only 2 components and no EMI emitting booster as opposed to 7 components of the suggested $4.50 solution.