fix(stm32mp1): correct dtc version check

Depending on the shell used, the grep command can fail, leading to
a wrong dtc version detection. Correct that by adding quotes.

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: I329ec929559c94bf1bf99b127662c9d978e067cf
1 file changed